Pretty good! I really enjoyed all the different ways scaling up and scaling down was used to solve puzzles.
I did run into quite a few bugs early on when I tried to collect the little measurement pieces. The elevator would not work no matter my scale, and I was able to scale up inside the small tunnel which causes my character to rapidly die and return to the start of the level.
Outside of the bugs this was great! I could see this mechanic making for a really fun platformer.