I'm in the middle of Dishonored on the 360 right now. If I had to lump it in with the Thief series, I'd say it's the second-best Thief game, behind only The Metal Age. I've been absolutely LOVING Dishonored, way more than I ever thought I would have before I picked it up. If you like Thief, you NEED to get Dishonored.
I agree with what others have said -- Blink can kind of make some parts of the game crazy-easy. The beauty of it, though, is the entire game is playable WITHOUT Blink, even though you're required to get it. If you don't want to use it, you don't have to. That, in and of itself, is amazing to me. The amount of ways in which to play this game is staggering, and you don't even have to commit to a certain way of playing for an entire level -- You can literally switch your play-style in the middle of a fight if you feel inclined to do so.