I hate that there's no stage selection so you have to play them all again if you want to replay levels. Also the loading of another level is really slow, I have time to read the poems till boredom.. But I liked the consept so much I played it through anyway. :)
I don't know if it's just me, but the puzzle seems to be playing on it's own. When I click a square I get the color or the x-mark depending which one is right. Instructions tell me that I should only get the x-mark with shift+click. I can just click on the squares and the game fills them correctly. Not much of a challenge there.