I loved it! seemingly because the AI following mechanic worked for me (mostly).
The 3d modeling is quite nice, the buildings and characters look great. if you had more time I would however add some more shadow or lighting to indoor sections as the doors can just fade into the wall of another room; maybe make a door frame that is a different color.
The animations are nice, but I do wonder if a swimming animation was worth it. I suspect you had some bigger plans for it otherwise, it's something you spent time on that might not be noticed by a good portion of players. That being said, because of that level of care for the animations I really noticed them, so double edged sword.
The AI worked for me for the most part. Early on she broke but was fixed when I came back to her. but later it took a few swings to reset her follow (somehow). If you could, it may be a good idea for the AI to wait for the player at a position, and after the path has been cleared for her, head towards the player where-ever they may be. biased on my experiences, this isn't how the AI is written, I may be wrong.
I enjoyed the play through, but I'm not sure it fit the genre. In a way you are gaining access to the map, but when I saw the 1st attack animation, I expected to get some combo by the time the game finished. If you were able to give the character some different kinds of upgrades I think this could be a great game to work on for the Super Metroidvania Jam.