Mechanically, this is a very interesting game. Each area is like leveling up two classes at the same time--you need raw XP to increase your combat power, and you need to succumb to the area's fetish to become more resistant to it (mostly). It's also funny to me that the girls have 4 active abilities and Special/Physical attacks like Pokemon, but I never figured out if elements (fire/water/holy) matter.
The first boss is perfect. Not entirely because of its own mechanics, but because there's an extra enemy with it. Classical RPG logic would have you kill the extra 10hp enemy first, to get ahead on action economy. But in this game that's suicide. Leave it alive, and it takes half of the boss's turns with its weaker abilities.
Most areas are built like time-wasters just to force you into enemy encounters, so you get corrupted through attrition. And most of the area fetishes aren't curable until you beat the boss and leave. This is most obvious with the hypno area, but is also pretty noticeable with the pony area.
This is not a complaint. It makes perfect sense.
Futa/Chastity and Pony were my favorite areas BUT both had similar glaring problems (shared with the Mummy and Fat areas).
The ability to cripple one character until you can leave (demon plug, slave collar) or a boss that instantly deletes one of your characters on its first turn. As fun as the progressive bondage of Pony was, the boss took me eight tries at level cap.
The diaper area, I just skipped. Not interested in what's in there.