I've never played Splinter Cell: Chaos Theory before, and I noticed it a mere $5 on Direct2Drive. (You can find the rest of the $5 games, in celebration of D2D's 5th anniversary here.) I figured I'd buy it since apparently it's an incredible game. (92 on Metacritic).
 
So I payed for it, and then figured the download would be rather easy, like Steam. Turns out I was wrong. It's even worse than the not-so-great new Gametap web-based format. The make you download a fucking zip-file. A zip-file? What? Why? Then you have to download and  install the stupid download manager and load the zip file into it so it can extract it and install it. Man, all you gotta do is on Steam is buy the damn game with your account, it'll add it to your list, and you click install, why does this have to be so hard? And I'm going to make an assumption that D2D isn't going to automatically patch it as does Steam, not that SC: CT has any patches coming out, but there's still 40 more $5 games to be released, so I might buy some of those regardless of the insane inconvenience of D2D.  
 
If I remember correctly, doesn't Steam like automatically activate your key if the game has one? I remember when I bought CoH it just automatically entered the key for me, I didn't have to copy it in or anything, well D2D doesn't do that. 
 
Also, the lack of community on D2D and not being able to talk to my friends when on Steam and see what they're playing and all that good stuff is also a huge loss.
 
I'm not sure why anyone would use D2D, unless it's an occasion like this where they have a great deal or for whatever reason D2D has a game Steam doesn't. 
 
Bottom line: Don't use Direct2Drive.

I've never played Splinter Cell: Chaos Theory before, and I noticed it a mere $5 on Direct2Drive. (You can find the rest of the $5 games, in celebration of D2D's 5th anniversary here.) I figured I'd buy it since apparently it's an incredible game. (92 on Metacritic).
 
So I payed for it, and then figured the download would be rather easy, like Steam. Turns out I was wrong. It's even worse than the not-so-great new Gametap web-based format. The make you download a fucking zip-file. A zip-file? What? Why? Then you have to download and  install the stupid download manager and load the zip file into it so it can extract it and install it. Man, all you gotta do is on Steam is buy the damn game with your account, it'll add it to your list, and you click install, why does this have to be so hard? And I'm going to make an assumption that D2D isn't going to automatically patch it as does Steam, not that SC: CT has any patches coming out, but there's still 40 more $5 games to be released, so I might buy some of those regardless of the insane inconvenience of D2D.  
 
If I remember correctly, doesn't Steam like automatically activate your key if the game has one? I remember when I bought CoH it just automatically entered the key for me, I didn't have to copy it in or anything, well D2D doesn't do that. 
 
Also, the lack of community on D2D and not being able to talk to my friends when on Steam and see what they're playing and all that good stuff is also a huge loss.
 
I'm not sure why anyone would use D2D, unless it's an occasion like this where they have a great deal or for whatever reason D2D has a game Steam doesn't. 
 
Bottom line: Don't use Direct2Drive.

Never used it, I thought it would be bad...I'll stick with steam, thanks for the heads up.

Direct2Drive is actually pretty decent, but you do have to install a download client (which also means using IE...ugh) and then manually installing the application. Not a big deal. Steam has its faults, too. Like games not being patched on Steam, even though there's a patch for the retail version. Or various types of expansions later on. And some degree of irrational censorship of content.
 
All in all, both are decent but neither are great. My personal preference tends toward Steam (where I have around 100 purchases) and then split evenly between Direct2Drive and Impulse/Stardock if Steam doesn't have an item I'm looking for.

D2D is a fine example of how not to handle digital distribution.

 (which also means using IE...ugh) 

I've only ever used D2D once, but I was pleased that I didn't need a damn client to run the game and that I could copy my game files as many times as I wanted using only Windows Explorer.
 
I do prefer Steam though, patching is excellent with the service. Let's not talk about Impulse...

for 5$ a game, its quite fine. I don't see myself buying regular price stuff on it though.

I saw SC: Chaos Theory, Rainbow Six and GRAW for free on these 8 Gig USB's at the Source (Circuit City in America I think) that seemed kinda new to me and slightly more convenient than D2D.

I'm stayin with Steam, that`s goddamn dumb, I could get the game free with less hassle of the pirate bay or something

D2D isn't bad. I used it to download the WoW client.

Yeah I didn't plan on using D2D either, even with the insane sale they're having right now. But that was mainly because I wanted to have all my games in one place rather than having to remember which games were where (made that mistake with Playgreenhouse). Thanks for the heads up though, the worst thing you want with a digital distribution service is a clunky activation and install process.

i'm getting bioshock for 5 bucks though
and that's pretty much the only reason i like direct2drive.

I picked up Civ IV yesterday for $5.  I was hoping that Steam might put a better package deal together as a sale, but no such luck.  For $5, I find it hard to refuse.  I didn't have much trouble.  It took a few hours to download on my crappy internet connection, but when it was done, I just unzipped the file and ran the install.  Some other program had to connect to the internet, which took a few minutes until my anti-spyware popped up asking me if I want to approve that connection.  And, yeah I had to open up IE (ugh, indeed) but I keep it around for reasons just such as these.  Once I did, everything went swimmingly.  I entered the activation code and was playing a few seconds later.  It's not perfect but I can deal with a little hassle for such a cheap price.  I wouldn't make it my "go-to" game store, but it's not broken either.

You've never downloaded a zip file before? Besides, you don't need to download their manager. You just need something like 7-zip to unlock the file. 
 
But yes, Steam is still better.