I kind of loved that the upgrades could make it difficult to get other upgrades (like getting explosions meant that I might clear my own upgrade slots by accident). It might have been a little too chaotic in this regard, and that would have bothered me in a serious game, but it was still a novel interaction that was surprising and fun.
I guess I loved that there was a commitment to using the arrows as the main means of interaction.
The kind of joke that I would personally find awesome would be arrow-based interactions that become absurd with more arrows or exploding arrows... like a William-Tell-Shoot-An-Apple-Off-My-Child random shop... where you get something if you can hit the apple and not kill the child.
The upgrades themselves felt like they resulted in some very satisfying strategies! Really impressive to have acheieved this in a jam!
If you spent longer on this, I think the area that has the most room for improvement is the enemy design and the level design. But for a jam it works super well!