How would you compare it to something like Fallout 3 or New Vegas? I haven't played any of the other mentioned games. I would give Deus Ex a try, but I'd rather not buy it since it's 11 years old. Human Revolution on the other hand looks cool, but vague on its release date. It is August after all.
I'm not quite sure how to size it up in comparison. The shooty bits are faster paced, like call of duty, and there aren't really "quests," per se. You do get some side mission, but the game is level-based, so they're entirely contained within each main mission map that they're found in. You do have to plan your character out, though, so it's sort of like the shooting of Call of Duty and the role-playing of Fallout 3/NV, if that makes sense.
And just to put it out there, even if Deus Ex is 11 years old, it still stands out as one of the greatest games ever made. It's only necessary to kill two enemies in the game (I think, it might just be one, haven't really played it totally pacifistic in a long while) and the universe is pretty unique. Human Revolution is a prequel, and it comes out on the 23rd, but I'd honestly say it might be worthwhile to look into the original first. If you get the Augmented Edition of Human Revolution, you get the GOTY edition of the first game for free, so no reason not to if you're going to buy it on Steam (only a few dollars more, discounted for preorders)
Hope that helps.
Personally, I had hopes for this game that it might sate me until Deus Ex 3 came out and it was a little fun to play but one thing that bugged me was how all the NPC's I ran into had that weird language in audio, even if subtitles were in English.
If it helps at all, the language isn't any one in particular AFAIK - it's a combination of latin and two others. So it's deliberate, and not a "developers were too lazy to get english VOs recorded" thing.