Finished it; very fun! Found the optional boss's cutscene confusing; the dialogue could use some polish there I think.
Also, I played a fairly completionist route both times, and the late bosses went down really easy, to the point that I'm not sure I saw either final boss's full moveset. I had to deliberately refrain from using the Cross on the optional boss in order to see much of him, either, which is a shame given how cool he was.
I also seem to have missed a health pickup for the sisters, maybe two or three given how small theirs seem to be. Not sure where to look, though.