The growing and shrinking mechanic was really interesting. I love the character and enemy designs.
Personally I'm not a big fan of the bullet sectios, I can struggle with fast reaction speeds and so that caused some frustration at times. I also think the difficulty and teaching curve ned a lot of work, there were a few points where I probably would have given up with the game if not able to get some help because mechanics were not explained.
However I did enjoy the base premise and think this would work really well with some level tweaks and some polish.