Children have a way of enjoying things that is very special. They learn about the world and imagine things in a way where everythign is fresh and new to them. I wouldn't claim that the Star Wars prequels lack the ability to capture the mind in such a way. I was even able to enjoy the movies on that level.

But, still, you can have a movie be fun for kids and still have it be enjoyable for adults (like Star Wars, ESB, and Jedi to a lesser extent). I think that's the main point of criticism for George Lucas. Otherwise, I won't detract from the obviously redeemable elements he has created.