I got the game recently and I just beat it yesterday.

[spoilers]I did both ending scenarios. After I saw the choice, I loaded my auto save file and made a back up and started it again. It sucks that there wasn't really a happy ending...or really much of an ending at all. It didn't feel like there was ultimate resolution this time around or like there was much of a bad guy. Dimitri was there here and there in the background but Catalina betrayed you at the start of III, Sonny was screwing you and taking a lot from you in Vice City, Samuel L Jackson was a pain to CJ from the start. I just felt like Dimitri was in the background for 3 missions and really didn't amount to a final boss or ultimate whatever.

Maybe in 360 downloadable content there will be a whole new set of missions where Bulgerian comes after you and your unresolved feud with him comes to a head and he gets more involved in screwing you over every which way. Maybe then more resolution would be felt XP[/spoilers]

Now off to do extra stuff and run around and kill people online XD Free mode sounds insanely hilarious XD Check out this glitch XD

YouTube - GTA IV: Skydiver