I enjoyed it quite a lot, myself. Unfortunately the majority of the appeal is in the story, and in order to upgrade your towns you have to be able to provide the right item based on vague hints, so it's not very accessible if you can't read Japanese as is likely to be the case for most people accessing it through QooApp.
It has a stamina limit but is EXTREMELY generous with battery packs... I was never forced to take a break and still had in excess of 200 packs when I finished... and the only monetization is a small amount of advertising. There's three endings, so make sure you keep going after you've seen the obvious ones.