IIDX Go(ooooooooooooo)ld.
I know this because it will be the one game released in 2008 which I will play the most in 2008. The end.
Rather than elaborate on that, I'll give my view on those initially listed -
GTA4 - Good, but flawed. Even though the game wore thin by the end it was still good enough to justify finishing at least. That being said, I don't forsee a reason to play it again any time soon, if not ever.
MGS4 - Watching the gf play through it was enough. Very pretty to spectate but I have no desire to play the game at all. I now know all parts of the story and me playing the game wouldn't really prove or expand upon a god damned thing, so why should I waste my time. Too much action and gunplay for a stealth game, as far as I'm concerned, as well. It also seems funny to me that for all the knocks GTA4 (deservedly) gets for its melee combat system, MGS4's isn't much more intricate. Is it supposed to be? I don't know. Is a protagonist in a stealth game supposed to be able to carry around several hundred pounds of guns on his person at all times? I don't know.
Bioshock - I'm still burned out on FPSes and the perpetual hype each and every one of them get. The game looks good and is well made but, again, I don't see a reason why I should spend my money or time on it.
Galaxy - A few minutes of playing this on a demo kiosk was all I needed, thank you very much. For all of the alleged brilliant level design, production values, soundtrack presentation, even the nice overall space motif which I do find appealing - none of that changes the fact that the game entails nothing more than you nagivating Mario around from Point A to B. I could give a shit about Mario. Moving Mario from Point A to B is no longer entertaining to me and not an activity which I deem worth spending my time and money upon. Super Mario 64 is the last Mario game I'll ever need to play for the rest of my life. Sorry.