Ooooh, do I love me a good logic puzzle game :D
I'm not sure why, but I find these colors very soothing; everything was just really nice to look at. The actual puzzles were also very enjoyable. I found most of them kinda easy, personally, though I was pleased with some real stumpers littered here and there (I was stuck on puzzle 40 for quite a while). The sound effects are also very fitting- subtle and never overpowering. I love the quick jingle you get on level completion.
That said though, the sound could be a little TOO simple at times. I almost feel like there should be some quiet ambiance music in the background. I guess the intent was to have sound that didn't distract you too much while you were thinking, but I can't help but feel it would have improved things a bit.
Also, as others have emphasized, the lack of a level select screen is reeeeeeeeeeally annoying. At the very least, it would have been nice to save your place, rather than having to cycle through all the levels you already beat when you come back.
Lastly, I found that completing the last puzzle was pretty underwhelming. I mean, really? All I get is a little text box saying I beat it? No celebratory animation or music as the credits roll or anything? Sigh... :(
Still, it's a pleasant little puzzle game that kept me entertained for quite a while. Good job :)