Finished a couple playthroughs of B-Prison. I liked it personally, I think it has a lot of good stuff and the art is solid. Unfortunately I found it falls into the common issue a lot of loss-related H-games have. It is way too easy. My first playthrough I did was essentially perfect. The 2nd I decided to never use more than 5% release magic and ended up going nearly perfect again. On the 3rd I found out you can beat the majority of the game without releasing magic at all...
IDK maybe it is just me but the whole point and allure of "leveling down" completely evaporates to me if you have to purposefully lose to experience it.
The bad effects were also sadly a bit lackluster too. Not in that they did exist nor in that they didn't do anything but they were kind of... self-contained to a level. Like you would lose and then the bad effect would be really severe (or with some, literally make the level impossible), but then if you progressed or went to a different level then it would be a non-factor so they didn't really contribute to a feeling of progressive leveling down.
Was still worth the play IMO. It is really short and quick so it isn't like it is a big time investment to give it a shot.