I beat the game with the Cleric class, and it seemed pretty easy since my defense was usually way higher than my attack, and I could restore MP whenever I wanted. I like the deliberately old-school RPG presentation here, and the mechanics work well for what it is.
I think if I have any critique of this game, it's that it got rather repetitive after a while. The enemies did get harder as it went on, but I still only needed a couple of strategies against them; even the Demon King went down in a similar manner as the cultists (which I guess the game tries to tell you). If the encounters had a little more variety, I think that would go a long way. Another thing that might help is if the environments had more of a sense of progression to tell you that you're getting closer to the Demon King; as is, it feels like you go through the same forests and plains until it's over.