I think he is great in spurts, but his streakiness suggests that it's not sustainable for 30+ minutes on a consistent basis. His defense is mostly effort-related (as he doesn't have superior size or hand speed), and his shooting legs are clearly afffected by energy spent on defense (and vice versa).
I do think he is a little foul-prone. When he was younger, I always dismissed it as "first year rookie/sophomore" call, but the foul rate still seems just as high, and they are often untimely.