imo the biggest issue with this game is that it punishes skilled players that advance really fast on early runs. It seems that each time you beat the bosses, the base game gets harder but if you beat the first boss on your first run you have absolutely no meta progression to supplement your power difference with regular enemies which is very frustrating.
This could be offset by making items much more powerful as well if you beat the bosses. Other than that, the game is super fun!