Excellent product that seems impossible not to recommend.
Chime is a pretty humble effort in more ways than one. The gameplay is simple, it's only five dollars, and it only has five levels. There's also the impossible-to-ignore fact that the developers have pledged no less than 60% of the game's profits to charity. I simply can't think of a reason not to recommend this game to anybody.
As I said, the gameplay doesn't take a 300-page manual to explain, but that doesn't mean there's nothing to it. The basic mechanics are simple enough, but some of the game's nuances weren't immediately apparent to me. It took me a handful of plays to realize how everything was working, and once you start trying to get 100% coverage on a level, you realize that this game actually packs considerable depth. I'm writing this review only having played the first level, but unless the four subsequent levels are just broken, I'm comfortable recommending about the game. I spent enough time trying to 100% the first level (which I haven't as of this review) that I feel like my 400 Microsoft Points went to good use (and then there's also the charity aspect).
Comparisons to Lumines are hard not to make (even if the gameplay is virtually the opposite), but the presentation is arguably more interesting. As the beat line comes across the play field, the pieces on the field each produce a different tone depending on where it's placed (and I suspect its shape matters as well, though I can't say for sure). This makes Chime half-game and half-sequencer/synthesizer, a concept I'm a huge sucker for (considering my favorite game is quite possibly Rez).
Chime proves that you don't need a complicated idea--or even a narrative--to make a good game. It's not guilty of being a simple proof-of-concept; I really feel compelled to get 100% coverage or--as is the case with classic arcade games--just keep playing because it's fun.
It's just so hard to say anything bad about this game. Unless you hate games or simply don't have the means to play it, I don't know why anybody wouldn't want to throw down five dollars for such a flawless product.