I just beat ODST. I think it has a campaign just as good as reach. The story was pretty amazing and I LOVE Virgil. Giving a AI emotion and intelligence was brilliant. 
 
I loved walking around the streets and all of a sudden signs started changing diverting me to the audio logs, which I found to be a fantastic side story that kept me wanting more and more.  The music was just amazing. I found myself just stopping and turning up the volume during some of the night mission songs.  
 
All in all i found it to be a great halo game.  But why do people not like it?

I love it, amazing game!
 
Now I'm a Nathan Fillion fangirl but the game was very cool to play, had a lot of different types of missions and the overall story/character exploration was great.
Ok the rookie is a silent sonnuvabitch but the rest of the squad was awesome.
 
Besides, I spend so much time in Firefight, that alone made ODST worth the buy!

People like to whine.

Halo > ODST > Reach > the rest  IMO
 
ODST was, to me, just damn refreshing. It really felt unique for a Halo game.

My two biggest problems with the game were being a human and therefore inferior in every aspect to a Spartan and the night time level design. I got lost so many times.

Personally, I really liked playing as the ODST's.  Not quite as irrelevant as a regular grunt solder, but not as 'OMG, super awesome' as the Spartans.  You felt a lot more vulnerable, particularly in the big fights.

I also really liked the campaign..  wondering the streets and riding around in the mongooses was great fun and the actual missions are among the best in the series.  Aside from maybe the original, I'd say it easily had the best campaign.  Oh, and firefight was a really amazing addition, even if the basic principles were ripped straight from Gears.

It should have been an expansion.

"It should have been an expansion. "

It's because ODST is by far the least fully featured shooter of the franchise.  Firefight was messy and not a whole lot of fun, and the only reason it can be said to have "multiplayer" is because it included a second disc with the exact multiplayer from Halo 3.  The campaign is in fact, the only original, even slightly good thing about it, which puts the game far below any other Halo game in terms of both quality and quantity of features.

People didn't like it? The response to the game was good. It was just a little bit short compared to Halo 3.

" I love it, amazing game!  Now I'm a Nathan Fillion fangirl but the game was very cool to play, had a lot of different types of missions and the overall story/character exploration was great. Ok the rookie is a silent sonnuvabitch but the rest of the squad was awesome.  Besides, I spend so much time in Firefight, that alone made ODST worth the buy! "

" @TaliciaDragonsong said:

" I love it, amazing game!  Now I'm a Nathan Fillion fangirl but the game was very cool to play, had a lot of different types of missions and the overall story/character exploration was great. Ok the rookie is a silent sonnuvabitch but the rest of the squad was awesome.  Besides, I spend so much time in Firefight, that alone made ODST worth the buy! "

Have you seen any Firefly? Nathan Fillion is amazing in it! "

I'm not a big fan, but I also feel like I didn't get a chance to play it like you are supposed to. I played Co-op with a friend who was hellbent on a clear time. I didn't get anywhere near the level of immersion or feeling of necessary stealth as others seemed to. To me, it just felt like another Halo game, which is really a shame. 

I liked it too.

For me, it just felt like something was missing. Can't quite put my finger on it, but it wasn't as vibrant as the main series, and the stealth stuff didn't quite work right.
 
ODST's are badass though. Getting Nathan Fillion, Adam Baldwin, and Tricia Helfer was genius.

Because.... 
The main games give you the feeling of being an invincible war machine with a thirst for covey blood, this game, you feel weaker. 
And, for me, I saw ODSTs for the first time in Halo 2, dropping down with me.  And they were useful if I remember correctly.  So I was like, "hey, these guys are almost as badass as the Spartans, maybe they should have been included as a player model in multiplayer."  But then you get ODST.  And you get characters, that are well, human.  One guy is in love with this other ODST, she is a total bitch, and not hot bitch where she takes charges.  She is just an asshole.  Other guys getting blasted and you play as a guy called a rookie.  When I used to think ODST, i thought badass without spartan enhancements, now I get called a rookie?  No, a badass, no matter what level, would not be called a rookie right? How could anyone that deserved to be called a rookie then even be qualified to be an ODST?  You get fucking dropped from the atmosphere into the fucking ground man. 
But I actually liked the sneaking approach, I loved how the game looked with the night vision on.  The firefight mode was pretty sweet.  I liked the maps on that better than those they have for reach. 

It was definitely overpriced. I liked how half the cast of Firefly voiced the main characters, though. 
 
@GunslingerPanda said:

" Getting Nathan Fillion, Adam Baldwin, and Tricia Helfer was genius. "

Considering I didn't buy Halo 3 (although I did borrow and finish the SP campaign from a friend), I bought ODST originally on launch and got a lot of value out of it that way. I thoroughly enjoyed ODST, even if I don't like the fact there wasn't any firefight matchmaking (and therefore didn't play it much after finishing the SP).
 
Maybe I wish I didn't buy it on launch, but still would recommend it heartily for anyone who just wants to play some more Halo.

I'm unsure I loved ODST it was my favorate halo in a long long time.

Because it was pretty damn short and cost $60 in the US when it probably could've been released at a lower price point. Granted, it was a deal if you hadn't bought any of the Halo 3 expansion packs since it came with all of them (that together cost a hell of a lot), but the features that weren't just Halo 3 multiplayer seemed a little half-baked. No Firefight matchmaking was pretty lame. Still, I enjoyed the story, soundtrack and cast they got together for the game.
 
Also, walking around the city at night could get damn boring at times, especially since you practically had to play with the visor on constantly or you'd just get lost.

$60 with most of the people complaining being the Halo 3 guys who bought all the multiplayer shit.@WinterSnowblind said:

" @ptys said:

"It should have been an expansion. "

It was a standalone expansion and didn't even cost full price in most counrties (was £30 in the UK). The campaign itself was too big to release just as DLC (double the length of MW2  :P) and if you hadn't bought any of the H3 DLC, then it was really great value.  If you thought it was too expensive in the US..  you would have had to wait a couple of weeks at most for a price drop?  It's not like the Reach beta started right away. "

" $60 with most of the people complaining being the Halo 3 guys who bought all the multiplayer shit. @WinterSnowblind said:

" @ptys said:

"It should have been an expansion. "

It was a standalone expansion and didn't even cost full price in most counrties (was £30 in the UK). The campaign itself was too big to release just as DLC (double the length of MW2  :P) and if you hadn't bought any of the H3 DLC, then it was really great value.  If you thought it was too expensive in the US..  you would have had to wait a couple of weeks at most for a price drop?  It's not like the Reach beta started right away. "

I think ODST took longer for it to go down in price being a Halo game.  If I remember most people complained about the 6 hour length on a harder difficulty as well as being Americans we don't care about the prices somewhere else.  I bet people in Japan are annoyed we pay less for more games. 
 
  Now I didn't play ODST so I can't make my own complaints.  He just wanted to know why others did. "

It is one of the games I got. I just need people to play fire fight with. 

" @SethPhotopoulos said:

" $60 with most of the people complaining being the Halo 3 guys who bought all the multiplayer shit. @WinterSnowblind said:

" @ptys said:

"It should have been an expansion. "

It was a standalone expansion and didn't even cost full price in most counrties (was £30 in the UK). The campaign itself was too big to release just as DLC (double the length of MW2  :P) and if you hadn't bought any of the H3 DLC, then it was really great value.  If you thought it was too expensive in the US..  you would have had to wait a couple of weeks at most for a price drop?  It's not like the Reach beta started right away. "

I think ODST took longer for it to go down in price being a Halo game.  If I remember most people complained about the 6 hour length on a harder difficulty as well as being Americans we don't care about the prices somewhere else.  I bet people in Japan are annoyed we pay less for more games. 
 
  Now I didn't play ODST so I can't make my own complaints.  He just wanted to know why others did. "

The game was at least 8 on Heroic (the standard difficulty). Which is the typical length for an FPS, if not longer..  Again, MW2 was barley 5. "

Most don't despise the game's for the quality, but for it's quantity. It was an expansion pack that full priced, and there wasn't enough content to make up for it. But I hear that the game cost cheaper in other nations. The game itself is rather superb, if it had only costed $40 or $30 (Well, at least in the U.S.) it would've go down as one of the greatest expansions made to a game. It's campaign was highly inventive, and a fresh change of pace from it's preprocessors. It wasn't as epic as Halo 3's campaign, but certainly more immerssive. It easily had the best storytelling in the series by far, it was even nominated for "Excellence in Writing" from the last GDC Awards. It's uniquely structured, the characters were well developed, it has better focused than prior games, and Sadie's backstory for the game provided a great backdrop for the story. It's story was far superior than Reach, that's for damn sure. 
  
My biggest gripe, apart from it's price, was the lack of matchmaking in Fire Fight. It would certainly garner less backlash from Halo fans, if it a half-priced DLC. Does it contain my favorite campaign in the series? I'm not exactly sure. I still argue with myself if I enjoyed Halo: Combat Evolved, Halo 3, or ODST's campaign the most. But ODST certainly has one of my favorite campaigns in the series. Hell, I enjoyed it more than Reach's campaign.

boring

I don't think it's that people on the whole didn't like ODST, I think it's just that people are expectant of an extremely high standard from Halo games as well as a lot of replayability. I thought it was a great game myself and while there were legitimate complaints to be made about ODST (e.g. The way the game encourages you to use VISR constantly doesn't let you see the picturesque environments as well) a worrying number of the complaints seemed to boil down to the game being somewhat detached from the Halo trilogy, you not getting to play as Master Chief or the game being too short. Personally I don't think these are real complaints and I think from the voice cast, to the film-noir inspired soundtrack there were many great things Halo 3: ODST did which some of the more mainstream Halo fans just didn't pick up on. //KEEP IT CLEAN//

I'd just played through the entire game yesterday...on legendary...in 4 hours.  Oh my god it's short.  It has fewer levels than any other Halo game and they each took 20 minutes max.  It was boring the whole way through, didn't delve into the Halo fiction at all except for the Virgil stuff and the epilogue.  Even those things were totally contrived though.  Also, what's with the lack of elites in the game?  This would take place at least a few weeks before the covenant civil war happened.  It seems to just be complete laziness on the part of Bungie then, that since there was no elite enemy AI programmed for Halo 3, that there wasn't here either.  I'd never played the campaign before this, but just assumed at least that part of the game lived up to the other Halo campaigns.  Oh how mistaken I was.  The ODST campaign feels like, and for all intents and purposes is, an expansion pack for Halo 3 with less substance than anything I would have expected out of Bungie.  I would be regretting this purchase if it wasn't packed in with Forza 3 and the map packs I was missing for Halo 3 for a total of $40.  It also helps that I now have both of those helmets unlocked for Reach and plenty of new spiffy avatar awards thanks to Waypoint.  Luckily, Reach is out now and oh my god is it fantastic.  Lets all go play that again and put the mediocrity of ODST behind us.