All I can say about this movie is this: GO SEE IT. I completely didn't expect it to be watchable and/or good, but me and Nathan had such a fun time seeing it.
I haven't loved the past few M. Night Shyamalan movies (I really only liked The Sixth Sense and Unbreakable), but this one's such a treat. Go, go, go!
(Sidenote: Have you seen Unbreakable? It's, like, really really good. Get on that too, if you haven't already.)