Not a bad try at fusing roguelike mechanics with a puzzle game mechanic. Pixel art is pretty decent, some of the music is a little generic to me but it stays out of your way while you're playing, so not much harm done. The biggest downside, though, is that the demo here at least is piss easy for anyone that is good at this kind of game (like myself). Especially if you get the needle power-up, any boss attack that shuffles the bubbles around becomes a near auto-win because after your shot the needle wipes them all out. I'm guessing that's known about and is why the needle is expensive, but still. Even on the regular levels it simplifies things a lot.
I never got in serious health trouble playing with that bomb guy during any of the playthroughs. That 2 bomb + gunpowder is a big boost to the point that honestly maybe it could do with a nerf to one bomb on harder difficulties.
Another thing is that there really isn't much in the way of *wow* in terms of playing, especially with bosses. It could do with some effects when they, let's say plant a piece onto the board it zaps on, or when it shuffles the bubbles shift around all crazy-like.
Maybe the full version does have that and it's just a demo thing, but despite the nitpicks it's still fun enough to spend 30 minutes on, which for a casual puzzle game in the modern era is an achievement on its own. If it was 5 bucks or so I wouldn't feel cheated purchasing the full game.