Nice take on the theme! The first one about popping balloons I've seen so far. The visuals were really good, as was the audio. The level design had a proper amount of challenge - it was easy enough to beat each checkpoint in 1-4 tries, but it would have been very frustrating if it was more difficult.
Criticisms:
Some backgrounds were too clear, they looked more like obstacles.
The checkpoints seemed to require a bit more accuracy than necessary, could use a more lenient hitbox.
Starting from checkpoint 7 the balloon often got thrown straight to the left, stuck between spikes and wall, which wasn't very fun.