I'll break this down and try to keep it brief.
Pros: + It looks great, even better than RE5. + Features most of the main characters from the series in a single game. + A large amount of content. + Combat is more fluid than ever. + Leons's campaign is good...
Cons: -...Chris's one is not. Jake's is meh. So that's near enough saying only 1/3 of the game is actually good (should have made Leon's 3 times longer and taken off the other 2). - Waaaaaay too many quick-time events. A lot of the game was broken up because of them. - Far too much action (thanks a lot, Chris). And if you are going to do an action/shooter thing, do it right. The cover system sucked. - Totally throwaway bad guy (at least RE5 had Wesker, but hey, he's dead now).
Bottom line: RE6 is the worst in the series. By trying to appeal to all audiences Capcom have shot themselves in the foot, and totally silenced anyone who still tries to claim the series is survival horror. It's not a bad game, but compared to the others, it's just really disappointing. Capcom should really just think about rethinking the series as a whole, because at the moment it feels like it has nowhere left to go but down.