I'm probably Duke's biggest critic, but I think he will get a lot better with time. Before ever seeing him play, I envisioned him having more quickness, better ball skills, and a decent jumper.
But Duke's really not that type of player. He's more of a PF trapped in a SF's body. I would love to see him model his game after Ron Slay or Charles Barkley. He needs to get stronger, develop better post up moves with his back to the basket, get more crafty with ball fakes to create open shot/pass opportunities, and work on his positioning for rebounds (which often lead to easy put-backs). I don't think he'll ever develop Slay's long-range shot, but Duke has a nice shot. It's not like his jump shot resembles Shaq's or anything. I could see him knocking down 10-12 footers with regularity if the PFs guarding him give him space.
I think it will come for him in the next few years. It's just tough watching him now, because you see the potential -- the execution just isn't there yet. He will be very solid in his Jr./Sr. seasons.