Thief 3 is my personal favorite thief game, because of the atmosphere. The game is dark, mysterious, creepy, but also absolutely hilarious. The voice acting and script from all of the NPC characters are so bad that they are good. My friends still quote NPCs from this game to this very day. The gameplay is fantastic, and I really hope that Thief 4 turns out just as well.
My initial reaction to the price was "why would they do this?!". But then I remembered all of the hours I got out of this brilliant little gem. I've beaten this game four times, and I come back to it every so often to beat it again. The art work is gorgeous, the gameplay can get addicting and the story, while cheesy, is enjoyable. This is one of my favorite games, and I recommend it to anyone.