I enjoyed the general controller feel, and the movement style was self explanatory, I don't think you even needed the tutorial card! It would have been helpful to keep track of the stars I've collected in the UI, as after dying, I wasn't sure if I needed to go back and collect it or not. When I first started, I hit the spikes and it lagged a bit as some effect was loading in - however it felt like I could successfully squeeze in between the points of a spike, and it felt kinda cool, given I was a balloon, maybe a fun idea to play around with.
Here's a playtest