Based on the improvements he's already made in his one year in the pro's, I think he's got huge upside. At the beginning of the year he was afraid to take it to the hoop. Now he's getting at least 1 and-1 per game and driving to the hole nicely. He's played solid D, but he could improve in that area. This guy can flat out ball.
The kid has his upside and his downside. Upside is that he is big and long and likes to play defense. No longer with Golden State fans have to worry about two 6-foot-3 players in the back court. Plus, he can shoot and drive to the hole. He has a nice outside shot and he is getting quite comfortable taking the ball to the hole and drawing contact.
I will not be surprised if Klay Thompson averages 20 ppg some time in the next few years - possibly even next year.
Downside is that for being 6-foot-7, the kid is not a very good rebounder. He can go in and get the ball if he absolutely has to, but from the looks of him, he would rather not do the dirty work. Once thing I will say for Monta - that guy could board BIG for such a small player.
He will get better and will be a very solid player for the Warriors. But he'll never be Kobe. The best example of what I think he will be is Paul Pierce without the athleticism or - better yet - Mike Dunleavy with an actual set of balls.