TL:DR: What starts as an innovative and exciting experience unfortunately ends up devolving into a mundane and messy one.

I appreciate the innovation when it comes to the platformer and traversal aspects, however the camera angle and movement made several encounters very janky, repetitive, and a chore. As for the battle mechanics - the forms and walls are a welcome addition. While I appreciate the wider variety of types and advantages, this turns into a spreadsheet headache if you care about battling and using that system. If you don't you can get through most of the game just using astral and plastic types. I think it would have been better served to narrow down on the available types and advantages and flesh out those options more to make battles more involved aside from spamming attacks and the occasional buff/debuff. The game also becomes very grindy and repetitive as a whole, fairly quickly. If you're someone like me and care about achievements/completion, you may find yourself dipping into QOL mods or the debug console to help expedite things. The art style was very pleasing - The music was not. It's not that the music itself was bad, it's just like 5 songs and thats it. 2 or 3 are mainly in rotation, with the hub town that you revisit a lot featuring one of them and it just loops, and loops....and...loops. The lyrics, the voice, it all gets really annoying 20 hours in hearing it over and over.

Play this blind I implore you.

Bought this to play with my friends.
Only to find out I cannot in fact play with my friends.

They can hover around you. They can watch your battles. They can battle you. They can trade. And you can team up for NPC battles -sometimes- but only when the game decides it's okay.
Not a great feature, not multiplayer. Might as well have just called it "Cassette Beasts! Now with online watch-your-friends-play mode!"

The feature is literally more equivalent to Pokemon GO than it is to actual multiplayer.