Signs is enjoyable until you think about it for more than two seconds and realize how dumb and poorly-written it is.
The Village is decent at the beginning, but then has one of the dumbest twists in film history.
Lady in the Water is maybe his most pretentious film (and that's saying something).
The Happening is also really dumb, with an even dumber twist.
The Last Airbender ugh. As a film on it's own, it's awful and if you're a fan of the show (like me) then it's downright infuriating. He couldn't have missed the point/spirit anymore if he tried.
Devil is ok, but hardly spectacular and it's got it's fair share of dumb stuff as well.
After Earth, I don't even want to speak of that one.
His problem, imo, is his massive ego. He really seems to think that he's some misunderstood genius who no one understands (see Lady in the Water for proof of that on-film), and that his movies being panned is due to people "not getting his vision" and no, well most people finding them to be bad movies. A good artist can accept constructive criticism and make adjustments. M. Night, he basically rejects ANY form of criticism and stubbornly sticks to what he's always done.