Perhaps this is just me, but I found this game to be incredibly frustrating but also insanely addicting. I've wasted many an hour on this game when I could have been doing school work, but that's my own fault.
The concept is good and the mechanics are fun and unique....except for the "squids (which don't even look like squids). I absolutely HATED the squids. They were really dumb and troublesome, and they creeped me out in all honesty. I despised them with all of my heart.
The ads were a bit annoying but not too bothersome; they were just a few seconds and a click from being disposed of.
Unlike most of the commenters here, I felt that the boards were often too random and the moves far too limited for this to be a mere test of skill. I often found that I was unable to complete a board unless I got extremely lucky, even with my hours of practice and my sharp critical eye. Perhaps I'm merely frustrated and pinning the blame on the game rather than on myself, but it really did feel like sometimes I couldn't win unless the tiles fell just right, even if I did everything I could to make just the right moves.
As for actual possible improvements to this, perhaps make some sort of preview thing, where you can mouse over the level to see what it looks like before clicking it, to save a bit of time when looking for levels to retry. Also, I would have liked to see some sort of way to mark levels as favorites. Despite my endless frustration with this game, I did very much enjoy certain levels and would love to replay them, but they seem to be lost in a sea of identical stars.
Overall it is a fantastic game. But very infuriating. I have a love-hate relationship with this game. It was "fun" while it lasted, and I'm glad I managed to finish it all over the course of a month (in between actual life, that is), but I never want to see it again.