Very fun once you get the hang of spellcasting. The idea and base gameplay are wicked. It's just so sick to open a spellbook in a game and actually have it be a book on information to cast spells, rather than a menu you dryly interact with to cast spells.
I didn't realize there were different biomes in different locations, so it took a long time for me to find any eyeballs or slimes, As a result, I played most of the game with no powerups whatsoever, which is actually fine if you get good at casting spells while running away in a straight line into a room you already cleared.
The spellcasting system isn't tutorialized so well. The patterns in the books seem to not match the patterns I'm supposed to draw. The text descriptions on the main menu are better, but sometimes are sporadic in what information they do or don't give me (for instance, the description to cast the basic air spell says "draw a line down" but the description for the electric spell doesn't specify which direction to draw the zig-zag in). It took me 20 minutes of consistent effort, educated guessing, and practice going back and forth between the game, spellbook, and main menu help screen before I felt confident about casting the most important spells (fireball, mana regen, and heal). Even then, I still can't consistently cast hex or lightningbolt, usually I'll cast these on accident when I am trying to cast fireball (and they do help me out).
What didn't help is there is no cue for if you successfully cast a spell with insufficient mana. So, at the very beginning there were times I was trying to learn the patterns for the spells, and I thought it wasn't recognizing my drawings, but I was simply out of mana and had no way of knowing other than looking at the indicator (which wasn't my focus because I was focused on drawing the spells).
It's a bit easy to get lost in the dungeon, and it can be a painful process to do so when your movement speed is very low.
Nonetheless, I persisted with the game, got the 100 coins, and beat it, and I had plenty of fun along the way.