Yeah, Johnny was very good in it. He's always very good about making his characters deep and unique. That's what I've always loved about him. But I definitely would have gone to see this if it wasn't Johnny. I didn't even know he was in it when I first heard they were making the movie.

Not to get technical... but I don't know how he would be diagnosed. I think he really only had two separate personalities... but one was a character, which was born out of himself. The other "self" he talked to was also himself... he was just debating himself in a auditory and visual format. In Schizophrenia, people hear voices in their heads and have hallucinations- which is certainly what he had... but he was also a writer, which, to me, comes with the territory to an extent. But multiple personality disorder is where there are separate people with individual names/characteristics/stories but they don't know about each other- which was how Mort & Shooter were during the film. SO maybe a mix of both. But I still only think he has 2 distinct separate personalities.

You should watch the extras and director's commentary on Back to the Future Part2. They spend most of the time talking about how they did the split scenes and wipes to allow the characters to talk to themselves :-) I learned a lot from that. heehee