Good surprise
Planescape: Torment- The more cinematic trailer for the game that came with Baldur's Gate looked interesting but I avoided the game since I heard bad things about Planescape. Eventually the game's price came down, and I picked it up as a "what the hell" sort of thing expecting a mindless dungeon crawl BG clone like Icewind Dale that was set in Planescape. I was very surprised at the actual game and started to love it about the time I talked to Dhall
Bad surprise
Master of Orion 3- I loved MOO1 and MOO2, but MOO3 was a steaming pile of... Needless to say it's a game that should be burned, destroyed, etc. Of course MOO3 fans claim that people like me are just ignorant and stupid because we don't understand the true nature of a Master of Orion game...