Basically, it's hard to imagine a better shooter. While J.J. Redick is human, you pretty much expect him to make it no matter where he launches it. You absolutely cannot play zone against him or the threes will rain down on you. One team made this mistake to start the game and about four threes later they decided to switch to man-to-man – it was too late.
A good man-to-man defender could possibly contain him, but it would be difficult to do for long because a) he knows how to run off screens, b) he has a quick release and c) he also has some shake and bake moves if necessary to get his shot off.
I wouldn't say any other aspect of his game jumps out at you, but he is at least adequate in all other respects. He may be a defensive liability against ACC caliber shooting guards, but it's too early to say for sure. I did notice that he was involved in one of those offensive/defensive substitution patterns late in one game, which leads me to believe that his coach doesn't think he's big time defender or rebounder.
Being a guard, I think he also might need to upgrade his ball handling and develop more ball quickness when out on a break. Overall, though, he is clearly an elite prospect based on his shooting skills alone. Unfortunately, great shooting is not a skill shared by many recruits nowadays, which makes him even more valuable. A guy like this changes the way opposing defenses play, so you could actually argue that his value is immeasurable. I can easily see why some rank him among the top 10 players in the class.