Having finished this, I'll say that it was better than I thought it'd be. The characters were pretty interesting. Obviously, the most interesting dynamic was Hibiki's relationship with Asumu. Maybe it was because it was just little tidbits, but I would sometimes find myself watching the other stuff just to see the development.
While Asumu becoming an Oni could've ran the risk of being the Justin of Kamen Rider, I was a little disappointed when in the end, he ended his training. The final episode was weird, but a decent ending. The movie was a little too random and too many coincidental character similarities. It didn't really feel like it added to the series any - other than origins of Takeshi.
Overall, it was nowhere near Faiz or Blade, but it was still pretty enjoyable to watch.