I'm a sucker for a good slowmo mechanic, so this was quite a bit of fun. Unfortunately it often felt like the hitboxes for the enemies / bullets were a little small and passed through when it looked like they hit (maybe I'm just biased because me aim is bad though :p )
I think having the cooldown between shots made each one feel precious so the slowmo felt vital, on the other hand it also felt like it slowed down the pace of the game a lot.
Really nice job!