Hm, honestly, I feel like there's no reason to ever stop shooting. Yes, the recoil is there but it's not really that big of an issue and your own movement can fight it no problem. Once you get the minigun and say sawbreaker on top of that, the game becomes trivial, because you can destroy most of the saws before new one spawn in. If there was an incentive to stop, I think it would help a ton. Have limited ammo that recharges when you stand completely still. Or ammo packs that drop in random places on the map. Or something more original... :D I realize my suggestions are pretty basic, but I guess you get my point.
Besides that, I think the game is still well put together! I think it looks really good, simple but it works. I like the shop idea as well, grinding a little bit to unlock stuff but for just that one run. I think that's really cool. Overall I feel like there's potential. Good job!