Yeah, The Love Symbol Album was probably his last solid work with Warner Brothers. After that he kinda went a little lax with his releases since he was so unhappy with their arrangement.
And, actually, now that I think about it, his NPG works were just as good as his works with The Revolution. It's just that some songs incorporated elements from the period that haven't aged well.
I mean, like, whenever I listen to "My Name Is Prince" and that rapper comes on, I expect the cast of "A Different World" to come dancing through the video or something.