Hitman: Blood money is the best stealth-action game I've ever played.
Graphics:
The graphics are pretty good, especially considering the release date. Character models are believable enough, and environments are good-looking. If you look closely, the graphics aren't as good as they seem, so just do yourself a favor and don't look that close and just play the game.
Sound:
Sound effects are good and voice acting is great, but a lot of crowds don't talk enough. Due to this, alot of places seem unrealistically quiet.
Gameplay:
This is where the game really shines. There are tons of ways to assassinate your target, ranging in stealthiness from running up to the target and shooting him to first killing his guard dog by feeding it a poisoned sausage then pushing your target off a cliff, making the death seem like an accident, and you walk out with no-one being any the wiser.
Buy or rent:
If you don't like stealth games then rent first, but if you do, then rush to the store and buy this game if you already haven't.
Buy it now. Its great, like Frosted Flakes.