The end was a bit disappointing. The entire story was very well-done, though, and I can tell it's going to have a fairly high "re-watch" factor.
The story was left on the open-ended side. Since the exposure of his secret identity is central to the climax of the story, there cannot be more story about Amaya Hibiki, cross-dressing teacher--at least not at that school--but there could be more stories about these characters, and there is clearly more story to be told.
I doubt we'll see more, though.