I've just seen the movie and I liked it. I was expecting a total mess from what I had read before, but I really enjoyed the story. It captured me from the first moment.
In my opinion, the special effects are the best thing of the movie: they are quite impressive. Shyamalan did a good job on this.
On the other hand, I think Jaden's performance wasn't very good, and for me that was the biggest problem: he isn't still a convincing actor. He sometimes doesn't show any emotion at all and has the same face in many (different) situations. He'll learn with time, though. The kid has talent.
Will's performance was okay. I'm glad he got so serious playing this role and that there isn't any comedy in his character. That made his acting better. Plus, his chemistry with Jaden was pretty good, once again, especially while he was giving him all those orders in the distance. There were some touching moments.
The music was excellent. Very epic. Great job by James Newton Howard.
Anyway, this is not one of Will's best movies. I think most people here will agree with that. And I think it's not Jaden's best movie either. He was better in 'Karate Kid'.
I give 'After Earth' 6.5 out of 10.