I've seen Psycho II
and it could hardly be called an "excellent" film. At best, it's okay, perhaps slightly better than the next two films in the series because of Vera Miles. All the sequel films really have going for them, of course, is that they talked Anthony Perkins into returning as Norman Bates. That was enough for me to watch all of them -- once -- but I can't imagine I'll waste time revisiting any of them.