Simple concept, very addictive! I've only tried this on PC, but it's a lot better on mobile I have to imagine. I loved the UI, and the sounds bubbles make when popped, really adds to the experience!
However, the numbers on the bubbles are changing too suddenly, in my opinion, it would be great to have some indication of how much time I have left before changing. Maybe replace the music and make the numbers switch in sync with the beat, so it would be easy to predict the changes if you have the sound turned on?