Ehhh...
"Grind-fest" is accurate. Playing around with this gameplay is neat I suppose, but it seems like there could have been things to make it more interesting, such as consumables you can activate or abilities with cooldowns or limits, bosses that do something other than stand there (I mean, you already have the ability to run back and forth, why not at least have them do things like jump or summon obstacles?)
The art for the enemies was enjoyable. I particularly liked the ogre.