nondeplumage: Never played it before. But it seems universally praised for being a fantastic game. 
  Well, Deus Ex gives you a great deal of freedom on how to develop your player character and how to proceed to meet your mission objectives. There is a great amount of variety in this game and how to play it . If you want to "ghost" the entire game, you (most of the time) can do that. If you wish to go in guns blazing, not giving a damn about security cameras and stuff, you can do that, too. That is the game's strength.  
 If Human Revolution manages to match that, I'd be extremely impressed.  
 Also: 
 - great atmosphere 
 - the in-game world reacts to your actions in a pretty convincing manner, sometimes noticing even the smallest details 
 - a very cool soundtrack  
 Oh, and the game is not based on any particular setting, but it takes its cues from movies like Blade Runner, Ghost in the Shell, etc.