I wasn't that impressed by Thumba... But yeah, the built-in auto-fix is nothing short of incredible. I've saved photos where the subject was backlit to the point of being a silhouette with it. And that's on an hd7! Every picture I take now, regardless of how good it may look to begin with, gets looked at with auto-fix just to see how good it *could* look. Only rarely can pics not be improved by it.
Also, it works on pics not taken by that device. I've managed to improve pics I took with my previous phone and then synced through my laptop.