I see a lot of negativ reviews, and soo I would like to leave a counter opinion:
Given that I had some warning that it would end abruptly, I thoroughly enjoyed this manga. In spite of clearly having to rush the ending, so many threads are woven together very skillfully. It is a shame we will never get to see what this could have been...
One critique I do have for it is that the ecchi elements, while beautifully drawn, are about half the time not even remotely related to the plot. Contrast that with prison school, where I feel like 98% of the ecchi was to setup layers upon layers for schemes of jokes and situations. That was missing here - it really seems like the author was just obligated to include it every once in a while, even if he wanted to something else with the story.
Oh well, regardless I am glad that I read it. Fare well everyone.