Very, very nice little puzzle game! I appreciate the item system, and the new rules. I've only won once so far. Sometimes it's impossible to correctly figure out where a secret room is, but there's usually enough advantages from hearts and items to make up for that frustration.
The one room I think badly needs a change is the Black Market. The fact that it works on a percentage chance rather than being fully consistent has ruined multiple runs. It's already not easy to triangulate which room would be the mid-point of several different rooms, so I don't think adding random chance to that is necessary.
Personally, I would probably give Angel Secret Rooms and Devil Secret Rooms one more rule, particularly something related to whether they prefer spawning next to a special room or a non-special room. It's not really necessary for smaller maps, but it would really help eliminate some annoying guesswork on maps with three separate floors.
I've only encountered them a couple times, but Red Secret Rooms are kind of awful. It's very easy for there to be *loads* of possible locations with only one correct, and they've eaten through my hearts. I'm not sure what could be done about this without changing their rules.
One more thing- I'm not sure if this is a known issue, but Hermit Rooms seem to work weirdly sometimes. I've had multiple games where they didn't seem to follow the room distance rule.