I bought this mouse as a replacement for the Apple Magic Mouse, which I find gives me hand cramp after prolonged use due to its very flat shape. This mouse, although very light, is much more ergonomically shaped, allowing you to rest your whole palm on its surface - much more comfortable than the Apple mouse (and yes, it works with OS X and Windows).
However, from the product images you would expect this to be a crisp white colour, when in fact it's closer to the off-white greyish colour of computers from the 90s. Just worth mentioning if anyone is buying this on looks.
But apart from its appearance, which doesn't really matter a great deal, this mouse is responsive and easy to use, and at this price, you won't find a better mouse. I'd tried using similarly priced laptop mini mice, and this is just so much better.