I think Bender is an interesting prospect. So far, in the few clips and things that I have seen, I see a very tall 18 year old kid who moves very well for his size, shoots extremely well for his size and age, but is week and somewhat gangly. In his current manifestation, he is not remotely close to NBA ready.
Now most 18 year olds are going to develop strength and coordination as they mature over the next several years. I am sure that will be the case with Bender. But the problem is that no one (and I mean literally no one) knows how much he will develop.
I would say that if he develops strength and coordination about like most 18 year old athletes do, he will probably be a fine NBA player in a few years. He already has a nice shooting touch and a decent feel for the game (again, based on a few clips).
My problem is that a #3 pick is in general too high a pick to risk on a prospect that still has to develop so much. I prefer more of a conventionally proven prospect with that high of a pick. It is a tough call. I would be fine if they got a good trade for him (say Okafor). Okafor is far more developed already and thereby represents far less risk (and maybe less potential reward I guess).