"Far too much fun...
Graphics
Pretty good for a multi platform release. In a way I was hoping for a bit more, but if you play this game in HD, everything is nice and sharp. The one area were the graphics reallly do shine is in its shadows and lighting, which at times can be absolutley stunning. Overall, while not groundbreaking, they do the job quite nicely.
Sound
All I can say is after the intro, the soundtrack did me in. I love the theme song for this game... Oh the rest of it is pretty good to ;). The sound effects are well done, with each gun sounding unique, to the way the noise muffles from a loud room to an adjacent hall. A lot of nice little touches in this department.
Gameplay
If you have only touched the demo level of this game, it is a far cry to how the rest of the levels are played out. This is a game where you can start a level, and if you want to be creative, you could easily spend 15 mins before you even do anything besides walk around and case the level out. There are a lot of entertaining moments in many of the levels, and so many times where you have so many ideas about carrying out a hit, you will find yourself replaying them many times. The AI isnt to tough on the games normal difficulty, crank it up to professional and you will see it react a fair bit sharper. Overall the AI gets the job done quite well, despite the odd glitch here and there.
The bottom line
I played through this game twice already and it is still stealing my 360 time. This is a game with a very high "tilt factor". This is one of those games that while the presentation is good, it will be the sheer amount of fun you have playing it that will keep you coming back for more. You could easily rent this game, and play it through (which is almost a must.). If your like me, you can easily justify buying it as its one of those games that you can play a lot when you get it, and even after you have done everything you can still come back to it from time to time down the road.
Sorry if the review was a bit quick and not to in depth, but I had the urge to play it again after typing the second sentence...:P
Hope it helps though!