the only thing about arriving early is you may still wait till much past your ADR to sit. so as long as you dont mind waiting, get there early.
the characters, expecially goofy, do come out to entertain the kids, we got many many pictures with goofy while we waited.
the day we went we had lunch reservations at 2:30, we got there at 2:00 and sat at 3:15. getting there early was a waste for us.