Not bad
The game itself was not too bad overall, but there were a few gripes I had with the mechanics of the game.
The main one being that you can't move and smash your hammer at the same time, which makes the game very boring at times.
The hit area on the enemies seems very badly done, and I get hit inconsistently, sometimes when I'm jumping on them even, so you should work on fixing that up a bit.
There were some other small things that were sort of off, but overall it wasn't bad.