It's is indeed and interesting, simple and addictive game.
What what most developers who make these types game don't realize is the potential of two things:
- Particle effects;
- Ambiance sound;
- Sound effects.
Look, if you used some type of soft particle system to make the bubbles disappear, it would look a lot richer and softer. If you used some kind of soothing background tune and would make up for a richer experience too. The current sound effects are a bit too hard/dry for such a soft looking game. Try the "pooof", "tishh" and soft "click" approach. See Thumblebugs gameplay on Youtube and imagine those sounds a little bit softer. That's what I'm talking about.
Cheers! Good job so far :)