These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
That One Boss: Demonica, by far, is the hardest boss in the game. You don't actually confront her face to face, but rather, the whole battle involves keeping her out of the room you're occupying. All the while, you still have to do damage to her and try to exorcise her.
They Wasted a Perfectly Good Plot: The game is just too short to really go anywhere, and after everything is resolved, there doesn't feel like there's any real resolution at all, just a credit roll march with Linda and her restored sisters.