I like the idea of a transformer kind of robot as a playable character, though the transformation itself was a bit underwhelming, as the only purpose seemed to be to get through small tunnels. I would have liked to see some kind of combat use for it as well, like ramming things. Or maybe just ramping over gaps or something.
The idea of the character losing all their powers is very classic Metroid, and I particularly liked the idea of having the player experience all the powers for a bit at the start, to show them what they're aiming towards.
The enemy and level design felt a bit flat for me; it quickly became a bit of a tedious affair to run one way, shoot some enemies that didn't pose any risk to me at all, and jump on some simple platforms, until I hit a block I can't destroy, and then go in the other direction and do it again. (And with some of the blocks, it didn't seem obvious whether I'd be able to destroy them or not, as e.g. sometimes the brown blocks could be punched to bits and sometimes not.)