I'm just going to give my thoughts as I play, sorry if this post is a bit disorganised!  This game is very charming and I think the art is really cute.  I also really liked the music.  It wasn't a huge deal but I couldn't pick my resolution (1080p) out from the list, more options for that would be great if possible.  I think you should have the bullet wave be telegraphed a bit better, whilst it does use predictable timing, having a visual and/or audio telegraph would help.  

The controls feel a bit floaty but they do the job nicely anyway.  It can get a bit annoying hearing "jump" everytime I jump, I'd rather just have a standard jumping sound than a voice line.  It's a very mild inconvenience but there's some kind of camera problem going on where it keeps stuttering behind when sudden movements are made like a direction change or jump.  

The shield jumping is really cool, I like it a lot.  There's a part where the camera zooms out for a big shield jump section that I have two problems with: first of all it zooms out way too much and is very jarring, the second problem is that the player can go off screen to the left or right, making it hard to see where you are.

I love the idea of different forms, one little suggestion I'd have would be to have some particle effects matching the element the princess is using, just to differentiate them better.  I think the difficulty ramps up a bit too quickly for a first level here, you're expected to combine both forms before you really get the chance to get used to the wind form, also the gaps you're meant to dash between the spikes with are too small imo.

I feel like the level design is a bit too open, it's cool to have a lot of optional things to collect but I was never really sure which way I should go as there a big differences in difficulty between each path, some visual signposting would help a lot, though I also think having the levels be a bit more linear would streamline the design and make it more cohesive.

The boss fight has the fire hit me before I can see it, I would recommend having better telegraphs here too.  Unfortunately I had to stop the game here because the boss fight wouldn't start on my 2nd attempt and I was continually taking damage and dying when there was nothing on screen.  I wonder if the fire hitboxes are still there from my first attempt but are invisible? 

Overall it was pretty good.  The theme was nice, the dialogue was funny, the art was very cute, the music was good and the unique game mechanics were good.  It just needs bug fixes, quality of life improvements and I really think it would benefit from smaller scale level designs.  3 out of 5.