This game is terrible.
I have a P4 @ 2.8, 768 meg ram and a Radeon 9700. In anything other than 800x600 with NO FSAA its unplayable. The "Bloom" effect is basically just a blur, it looks horrible on a PC monitor, it should have been switched off by default, especially as it breaks FSAA. The graphics are nothing great to begin with, there are stencil shadows all over the place, but the poly count and texture resolution is very low, with bump mapping and specularity only on a few select surfaces. This game was released unfinished. The game doesn't even save your game settings because it installs one of the ini files as read-only and you have toggle the file manually. This just stinks of something not properly tested before release.
After I messed around to get it to run I did sit down and play the game for 4 hours. Its a let down. The RPG elements are dumbed down from the first one. The branching story-line isn't. For example, after the first "mission" of the game, your partner tells you she has join some cult and suggests you go to your bosses former office and snoop around. You don't get a choice to say no, your objectives are just updated automatically and you have to do them. The AI *IS* terrible. I attacked a guard with a stun batton and he says "okay, you need to stop that". After I knocked him out I carried his body passed the other guard, who didn't seem to notice. I then blew up the door to an apartment with a grenade, and the other guard comes running over, weapon drawn, but then doesn't attack me. After that I lost interest, killed everyone in site, then quit and this game is getting uninstalled.
Despite its dated Unreal engine, the first Deus ex is a much better game.
I'd save your money for something better, there are some good games out atm. I recently got Call of Duty and NFS Underground, both very good games.
Core2 Q9400 @ 3.0, eVGA GTX 260, 4G DDR 800, Vista64