We've done this three times. Twice we had the Fairy Godmother and once we had Alice. It is cute, but I agree with RMulieri who said it's not worth going way out of your way for it. I do think, though, that if you have young children,they will like it.
The younger kids get to go up front and listen to a story by the character. After the story is over, you can do autographs and pictures. They do not rush you at all, and it's a very relaxing and calm visit. There are also lots of photo opportunities in the theatre itself (which is tiny by the way) because there are large cut-outs from various Disney films. My kids had fun posing for those pictures too.