It is quite cathartic making the numbers so big they start crashing the browser. Also something about manipulating the nature of a self-replicating physicsball population to maximize the points feels good up until what's happening becomes impossible to discern.
I found the sound for the balls bouncing quickly became popping fuzz, which became a little unpleasant on the ears. The music is also quite loud and some of the buttons started growing off of the screen, making it hard to tell how many 0s were in each upgrade.
The upgrades themelves feel fitting and scale appropriately. The idea of growing the balls and then having them do some kind of mitosis brings up some interesting questions about the biology of the ball which adds some fun.