I've always been a fan of Microsoft hardware products (mice, keyboards, webcams etc.), as the build quality seems to be the best available. My wife bought me this mouse to use with my MacBook, as I'm not a big fan of the Apple mice.
The thing that most surprised me was the size of it. Because it's intended to be portable, it's pretty small. I've not got the biggest hands in the world but it is only about the length of my two 'mouse fingers' (index and middle). This means it is too small to be comfortably used for long periods, and I tend to not bother using it at all.
The bluetooth connection is great, however I've only ever tried it on a Mac. Here it works out of the box, there is a downloadable driver from Microsoft, but I've not tried it. Unlike the Apple mice, it doesn't report battery life to the Mac, but the 2 AAAs seem to last for ages (perhaps because it doesn't get much use).
On the build quality front, I was impressed as always. I'm not sure how it happened, but it got dropped into the kitchen bin, and had to be rescued from the outside wheelie bin. After nearly a week in with the rubbish it was a simple task to clean it, since Microsoft still use screws to hold their products together. After dismantling and cleaning the parts, it was reassembled, and has worked fine ever since.