Yeah, the anime is certainly enjoyable for a few episodes. But the ending just screws up everything. It made me feel like 'why did you bother making 9 great episodes if you want to made the end super bad?'
I doubt the anime will ever get a second season(Pretty sure that it won't). Izayaoi is certainly overpowered but character development is poor-- Mondaiji-tachi is one of the good examples of overpoweredness done wrong.
Its fun to watch but only if you manage to turn off your mind. There's a lot of obvious plot-holes so once you start thinking while watching, you'll be like, "How the heck is this happening?"
I have no problem if anyone is watching this, but if you want to at least have a good impression of the series, stop watching the series at episode 8 and fantasize about what's going to happen next. The end is crap.