I gotta be honest, this was surprisingly addictive. I found myself spending far more time on this game than I should: the graphics were bright and inviting, the music was a nice little mix (though I could have done with a liiiiittle more variety - three or four times through the mix, I had gotten the point), and the gameplay was deceptively simple. In many ways, it reminded me of your basic match-match game, but the added rules and gradually increasing difficulty took it a step above.
The only real suggestion I can give is that I could have done with an in-game tutorial - it's a bit daunting when the instructions seem to be just a massive wall of text, and while I picked up the gameplay fairly quickly, it took me a round to figure out that there was a limit on when you could pick up the heart bonus (I haven't played the first game yet).
Otherwise, great game!