I just finished the demo. I did enjoy it, but I hated the controls. I've played worse, though, I just didn't care much for the camera control (I also like being able to remap keys while playing the game). I'm not sure if this is a buy yet. I kinda wish the demo included at least one castle upgrade (not counting the portal). Oh well.
Like I said, I enjoyed the demo. I really liked the goblins bringing me the little yellow orbs.
Spoiler:And seeing the horde of goblins all over the last guy was kinda cool.