I'm honestly happy with this ending, Mizutani the crazy teacher got a proper punishment, - though, honestly, I would fire her instead of what punishment she got... - Kataoka stopped himself from having sex with Kaoru before it was too late, and he finally revealed everything to Yuki.
Kataoka got so much punishment from everyone, literally punched across the room by Kaoru when it was revealed by Yuki that they had been living together, punched again by Yuki when he revealed to Yuki what he had done and how he had kept the truth from him all this time. Kataoka even got pushed into the pool, albeit the kiddie pool, by Yuki when he revealed to Kaoru the truth of who Maa-kun actually was.
While I was waging a war against myself about who I wanted to see Kataoka end up with between Kaoru and Yuki, there was also a time before Kataoka doing the right thing that I wanted Kaoru and Yuki to end up together, leaving Kataoka alone in his misery for the selfishness he had portrayed all the time.
But given all that Kataoka ultimately ended up doing in the last few chapters to correct the wrongs, even knowing how it would most likely cause him to be lonely and hated by everyone he held dear, I'm glad that Yuki managed to come to terms with the fact that Kataoka wasn't actually the Maa-kun that he remembered from his childhood, and that he didn't decide to pursue Kaoru after finding out about her being Maa-kun instead, and instead of doing that, decided to actually help out Kataoka by placing the both of them in a situation where Kataoka could sincerely apologize to Kaoru and make up with her, ending up becoming a couple again - this time for real, no secrets had between them.
While Yuki ended up alone in this case, I have no doubt that he is quite happy now, being able to live as the girl he always wanted to be ever since meeting Maa-kun in his childhood, and becoming so popular that practically all the school wanted to date him.
Oh, and also Hidepon ending up with Yuki's cousin was bound to happen ever since their first meeting, I'm just glad the author made it happen, that big ball of caring deserved a happy ending, too ^^