I blew through it last week and clocked in about 16 hours after replaying a few of the levels to try a more stealthy approach (I originally just blasted through the levels, killing everyone).
Overall impression is that it's a very fun game. Gunning people down in this one is extremely satisfying, not to sound like a psycho or anything, but it is. Graphics are amazing, and (especially in the Chinatown level, imo) they do a decent job of setting the mood. Unless I'm mistaken, the composer was changed for this one but it's pretty darn good with what direction they decided to go in. Still, most of the levels in Absolution lacked the punch most of the levels in Blood Money had.
Other than that I agree with fistfulofmetal about the lack of variety in how to eliminate targets. There's usually like two or three ways to kill someone in Absolution versus the four or five in Blood Money. Generally, they aren't as interesting as well (i.e poison, falling light fixture, sleeping pills). I'm sure the replayability of Absolution isn't going to be harmed too much from this due to the whole Contracts mode, but it is just plain disappointing for a Hitman fan.