Here's the thing about this movie...the concept is out there. Maybe a little too out there for it's own good. That said, as in all of M. Night's movies there is some really good character work being done in here.
One of the things that makes his movies good is that they're never really about what they're about. Signs isn't about alien invasion, the sixth sense isn't about ghosts, unbreakable isn't about super heroes, etc. Along those same lines The Happening is not really about, well, what is happening.
The Happening is about the relationship between two people who have just gotten married and aren't really sure about themselves yet. It's a relationship at that shaky moment where at any second it could fall apart. The 'event' in the Happening is only a catalyst that helps them to find out if they really do love one another.
If you watch it for that plot line you will probably come away satisfied. The movie builds to a very nice climax where the characters make an important choice that will probably forever define their relationship. It's a powerful moment of hope, hoplessness, and above all love.
Don't misunderstand me. This is not M. Night's best work. At times he seems too caught up in the big events and looses sight of the people. Too much time is spent trying to explain what is happening, but every explanation just sounds that much more forced and the actual explanation is just hooky to the point of making anyone who thinks about it too hard laugh out loud.
He should have taken a cue from his own play book and used the age old horror adage of leaving the cause of 'the happening' to the imagination. It doesn't really matter. What does matter is the people and the relationships and sadly they aren't as well developed as they could have been because of all that time trying to explain why.
As my final thoughts on the subject I would like to plead with anyone who reads this review to give the movie a chance. You probably won't like it. Most people don't seem to. But if you look in the right place there is something worthwhile here.