Halo 3 was everything I wanted and more it was awesome.
The singleplayer campaign is fun with a very good story and compelling characters. The action always sucks you in each little skirmish is a little different and the game only gets more fun and challenging as you progress. There's not much more I can say for the singleplayer it doesn't stand out in any particular way except for some awesome four player co-op action, and cool cameo's from Firefly/Serenity characters, and the skulls/easter eggs of course which have always been cool in the halo series.
Like halo 2 multiplayer is really where this game shines, from slayer to rocket race (hella fun), it offers some very diverse gameplay for every level, I can recommend this game to any shooter fan because of it. The weapons are mostly the usual halo array of cool futuristic versions of normal weapons, save the new brute weapons (spike grenade, so cool, awesome), and the hammer of dawn, oh sorry, sorry I mean Spartan Laser, and they're still so fucking cool. Each map is cool and fun with though the downloadable ones were a little iffy to me but whatever. Take my word for it the multiplayer is kickass and totally worth every penny I payed.
The graphics are pretty awesome, especially the cut scenes, and I gotta tell you each explosion is a work of fuckin art (like when four plasma grenades, and a couple plasma coils go off together). The characters, including the elites display emotion very nicely, along with good lip syncing, and those little indescribable quirks that make them feel real. The voice acting is great especially the firefly cameos mentioned above, Truth does have a new voice which is way better, master chief is still so awesome looking, his armor looks much more torn up and as a result much more badass. Each weapon has a good sound which feels appropriate for each.
Both the single and multiplayer frame rates are stable only just a little shuddery when some seriously crazy shit happens, (like when ten grunts all die in a gigantic explosion from four plasma grenades, a few plasma coils, a couple brute shots, and some rockets oh Co-Op is fun). Speaking of Co-Op it's a very nice feature and makes the already fun campaign better, and even with the four players the game still performs nicely (except for when some seriously crazy shit happens). It's not too terribly laggy better than alot of other games I've seen. Overall this game performs to the extreme and pushes the 360 to it's potential.
Definite buy, this game is fun period, the multiplayer is of the highest quality, the graphics and art are kickass with good sound to match. Go to the store and buy it now or no soup for you.