I like Barnes and I think he will be better than Marvin Williams. I think he has a good handle, shoots well, and is an aggressive rebounder. However, I think Derrick Williams will be a better pro. It will be interesting to see if as many freshman come out as people think. If I were Barnes, i would stay in school because there may not be an NBA season next year. If there is an extended lockout, it could ruin a lot of kids careers if they come out too early.
They are very, very different players. Barnes is a natural SF in the NBA. He has a lot to learn but he has a natural position.
Derrick Williams is a stuck between positions. He isn't tall enough to be a 4 and will need to develop a lot of perimeter skills to play the 3.