There are games, and then there's Deus Ex...
The gameplay itself is unique and borrows from pass success of System Shock and Thief series. Deus Ex is best summed up as a sublime first person immersive experience. The storyline is nothing short of epic and grip you and make you want to play till you complete the journey.
Really there is no reason why you shouldn't play this game. Even though it came out nearly 8 years ago (2000) it's still my #1 all time game, in any platform. Long live Deus Ex!