Very simple and fun. The bosses were really easy so I would have liked a difficulty scale a bit. For over half the bosses I just stat checked them standing still and shooting. I think that is a product of many of the bosses being almost identical in their attacks. Best bosses were lust and envy because they forced you move around and dodge to avoid damage. I really like the vibe of the game and the simple upgrade system was nice.
Funnily enough my game has a similar premise where you fight through the circles of hell (from dante's inferno) so kinda the same vibe as fighting the deadly sins.