From a technical point of view, there's some highs and lows here. The highs are that the graphics are much improved over the first game [probably even nicer if you have a rig that can handle the ubersampling], the animations are more fluid and offer more variety, and there are some really nice looking character faces. The lows are that there's still something that doesn't quite feel right about the camera and the way it moves [seems kinda jerky], the dithering [enough said], and the controls sometimes don't feel quite as responsive as they should be [sometimes if you get too close to a door the icon won't come up, going from swinging to rolling/parrying often feels way too sluggish, ect.]. So, it's a bit of a mixed bag there, but mostly big improvements and no real game-breakers either.
I've played about 6 hours, had it crash twice at random moments [once in combat and once just walking around].
Performance is pretty good. I've got most things turned up [on my Core 2 Duo/GTX460] and have been getting a framerate that I have no problems with, just a few odd hiccups here and there that feel more like engine issues than resource deficiencies.