I enjoyed this film, and I would recommend it to the young and old. It would be perfect to watch if you are a high school student. Even now watching it as a young adult, it's a very cozy and youthful film.
I would've liked to see some more interactions between Muge and Hinode, especially after they return to humans. However, both depicted young romance well, and I could relate to them. Also, I would've liked to see a bit more exploration of Hinode's characterisation such as his personality, emotions and inner thoughts (e.g. how he really feels towards Muge).The animation should be highly commended. I paused and re winded many times just to soak it in because it felt so surreal. I found the simple plot refreshing to watch.
Finally, if you love cats, you have come across the right film!