It was a fun diversion and felt very metroidvanish. It's hard to judge the assets, as they are external (which is OK, especially since there are 4 engineers writing a game :).
The only gripe I have is that when I arrived in the boss room, the door closed behind me and the room was closed. I then realized that there was a big guy running around in spikes in the room before - probably the boss escaped its enclosure and soft-locked me in that room.