So, starting off on a strong point: game has no bugs, and is playable which is a good standard for jams. Loss screen, and (hopefully) a win screen. I didn't end up finishing the game because I got to the last level and just did not want to deal with the skulls. :P
I really liked the game. I think the cute-morbid aesthetic was pretty charming, and I think it worked well with the mechanics and difficulty.
The difficulty was pretty bearable. The obstacle in the first stage is a little hard to see so I (and my wife) both died there before we figured out what was hurting us. Overall though, I think it was a pretty reasonable difficulty curve. The (presumably) last level with two skulls firing out of the wall at the same point made me stop playing, mostly because I didn't know how I was supposed to deal with that. They didn't seem to be blocked by terrain, boxes, and the ol' reliable "jump on their heads" move wasn't working for me.
The music was simple, but nice, and the SFX felt on-theme as well. Overall, it was pretty good! Good job!