I agree and I think some of the real-world manga problems that we see through Shinobu affected this manga, in the end. That is, Shijuukara got the ax at the production company for whatever reason, and Sakai Eri was left scrambling to finish.
I appreciate that we got a capstone happy ending that's fairly open-ended. It's better than a lot of Japanese endings that I've read, at least in those respects.