I have never played the original, but really enjoyed the sequel “Deus Ex: Human Revolution”, it is probably the last game I really obsessed over. I played it beginning-to-end several times finishing all side quests (I'm a completionist after all). It wasn't perfect, I thought (like most people) the boss fights were not in style with the rest of the game and the choice at the end wasn't consequential. But the game and the gameplay itself were great.