The campaign is around 12-15 hours, depending on the difficulty you play it on and if you want to collect all the bright shiny things to upgrade your weapons and shield. Whilst the gameplay might not always be the smoothest, it is varied and always exciting, especially at certain points in the story where it can be very tense. The whole game is designed and looks beautiful, and some of the sights are breathtaking, a much better looking post-apocalyptic world than that of Fallout. The acting is flawless and you grow to really care about the characters throughout the game, which in the end is why you should be playing the game. It puts a new exciting spin on a very over used storyline and the ending, without spoiling anything, is not what i expected, but still absolutely incredible and better than what i imagined. From anything you might have seen from trailers or gameplay, you haven't seen anything..trust me. The last few levels are absolutely huge and brilliantly designed and at this point any small flaws or problems you might have with the game, will be overlooked instantly. So this game might not be COD:Black Ops, (even though it does include some quite frequent third person shooting), this game has emotion, looks, and a really fun experience.
I can't believe how under rated and overlooked this game is by the gaming community, and this game would make a brilliant christmas present, especially now it's been reduced nearly everywhere. If your a fan of action, adventure, a good storyline, good acting, or even art this game is definitely for you.