I also had problems with the attack. It didn't feel very responsive and sometimes wouldn't strike more than once. The level design was interesting. I had fun carrying the rock around on my back for a while, but was sad to see it didn't respawn when I died. :( The rock did look a lot heavier than it felt.
I liked the music. It felt very fitting to the game.
I wished I had been able to find the wall-climbing ability. That sounds like it would be fun to play with.
Good work! I hope you keep developing into a full game. Would love to see it!