I've played every CoD Instalment from Call of Duty 1, and I'd say that Advanced Warfare is the 2nd best in terms of story (after the Modern Warfare series). The story has quite the plot twist, and is interesting till the end. However, the game seems to have many negative reviews because of the difficulty levels (?). It is true that the exo upgrades, threat grenades, smart grenades and certain abilities like STIM make veteran difficulty a bit easier than AW's predecessors, but I don't think it makes it THAT easy as most people say. You still have to play carefully, and avoid taking too many hits, and watch out for them melee attacks.

Also, I find the single player campaign of this game VERY good achievement hunters as you can complete it in one go, though I am going to do it in two go's (1st in Recruit with all the other achievements + intel, then the campaign in Veteran difficulty).

TLDR: Good game, good for achievements, but you "hardcore gamers" may find the Veteran difficulty a bit easy :p