First, a few caveats:
1) I have never played previous Hitman games.
2) I bought this game on sale for 40$, not full price.
3) I am playing the updated version...1.02 I think.
The premise of this game is that you are an assassin who has to assassinate people. There's a plot, and a raison d'etre, but none of it makes any logical sense.....but that's okay. It's a playground! And it suceeds very well!
The gameplay is a lot like a Metal Gear Solid type tactical stealth game - you sneak about, distract guards, take out a target, and get out. The levels are large, involve multiple options, and encourage creative re-play for high scores and laughs.
That being said, the game loses focus at times and becomes a run-and-gun shooter, and drops the whole "assasin" angle completely while you run from helicopters for some reason. It's weird, but doesn't kill the experience. It's just not as much fun to run and fight as it is to sneak around back alleys hunting a target.
The graphics (on PS3) are good, if a bit dark (but.....you lurk in shadows, so that's kind of appropriate). The environments are interesting and somewhat varied.
I give it a 3 of 5 for losing focus at times, but still being really fun.
(Note that I purchased this game on sale for 40$, which I feel is a fair price. I would not consider 60$ a good price for this particular game.)