Don't buy Mass Effect 1, Alan Wake, Metro 2033, Splinter Cell: Conviction, Two Worlds. Do buy Crackdown, Fable 2, Gears 1 & 2, Tales of Vesperia, Lost Odyssey and Mass Effect 2.
The 'don't buy' games aren't worth the full purchase, Alan Wake and Metro 2033 are great games but both are worth a rent unless you find them cheap. Mass Effect is broken and extremely overrated and unless your planning to play online Conviction single player is really short.
The 'do buy' games are all great and can all be found pretty cheap (besides Mass Effect 2) and there all long and great experiences.
Enjoy your 360 and don't jump on to every exclusive people in this thread mention, people tend to give more credit to some games than they deserve. Research is recommended.
Bet with Conegamer and AussieGecko that the PS3 will have more exclusives in 2011 than the Wii or 360... or something.

















