Watching the prequels first pretty much destroys everything Darth Vader was thought to be before in the original trilogy. It's no longer a surprise when Vader reveals he is Luke's father and Vader looses a large portion of being one of the greatest villains in film history. He becomes a tragic character and not the man in black who was a force of evil. Knowing that the goofy little kid in The Phantom Menace is the guy in the suit just makes me sad.
I don't know any adults who like the prequels, so that means there's hope for the children of tomorrow. I'm thankful for having been born before the re-release of the VHS tapes and growing up with the true trilogy. Even though kids today will now have two different parts of the saga to watch, I have a good feeling that most parents (if not all) will introduce their children to the good Star Wars movies first, and if they want to, the prequels eventually. Only to have those kids grow up and know which films are the best and continue this pattern in a never ending cycle. May the force be with them.