I read Demiurge right after I played the original Deus Ex for that reason. It was a masterpiece.
Haven't had the chance to read anything by Chris Todd yet (the writer/curator of all the snippets you come across within the game, as opposed to the plot itself), but I remember enjoying his in-game style a lot too at the time.
If anyone else is a fan of the original Deus Ex, one of the writers for it, Sheldon Pacotti, has been writing science fiction for years:
http://sheldonpacotti.com/