A bunch of reviews are up...

http://www.gamespot.com/pc/action/thief3/review.html

http://pc.ign.com/articles/518/518951p1.html

http://www.1up.com/article2/0,2053,1600847,00.asp

Despite my anticipation I'm not going near this title until it's been patched at least once and the Thief community creates a similar performance tweak applet like the excellent one that came out after DX:IW hit the shelves.