I'm pretty sure if he walked through the gates of his original park, he'd be comfortable enough with what was done with his creation.
Best cover the ears of the children when they explain that the park is no smoking, and might want to turn up the TV for a while as they explain what happened to his ideas of Disney World and what Roy did do it.
Hopefully they'll tell him about Disneyland Paris while he's in a plane...
All in all, I think that at least the original park has kept to the ideals he put forward.
Well, I have never been to the one in Anaheim, but I can deduce from your comment that they have more-or-less preserved the original design.