Very cute and full of charm.
I was really into the concept at first, but unfortunately with how much XP you need you have to spend way too much time just scouring the world for things that won't kill you (and the weakest targets available are usually still ones you have to do a lot of math with to manage limited HP). It got to be too much for me and I couldn't finish it.
Other than that, it's a concept with a lot of potential, I'd like to see more games like this.