He's good (but ugly) fron 15 ft in. Anything further out is ill advised. His release point is the problem.
Fundamentally, even the way he brings the ball up in front of him is a problem. There was a picture that that St. Jon's posted on twitter I think that showed him putting up a shot... The ball was still in his hands being brought up to be released... It's hard to describe, but it is ugly. He's flat out just readying his shot in a wrong way. Somehow his shooting elbow is not straight below his shooting wrist... and the ball is awkwardly positioned in his hand...
You can tell he hasn't done enough on his jump shot form, because the ball rotates oddly every time he releases the ball. It's really a shame. I'm rooting for him so hard, but his jump shot form is going to keep him from making as much money as he could maximize. It's really too bad.
There was a picture of it, and I saved it but I don't how to paste into this forum or else you could see what i'm talking about.