this game introduced the stealth genre to me, and its 100% worth what I paid for it!
Gameplay (9/10) you gotta be stealthy or you'll fail the mission, if you don't knock out a guard before he signals the alarm...you're screwed. Some missions you won't be allowed to use lethal forces (your pistol), some missions will take 2 or 3 screw ups to fail the mission. Either way, its addictive and fun.
Graphics/Sound (9/10)
Comparing the graphics of this game to other ps2 games, it totally deserves a 9/10, your most likely not to find a game on the ps2 that surpass these (except maybe the MGS series).
Quality (10/10)
The A.I. is intelligent and I've never seen any bugs or glitches in this game.
Story (8/10)
This game doesn't have the best story out there but its good enough, you'll make a connection with the characters and you'll grow hate for your enemys.