I bought this mouse from a local store. It's a few quid cheaper on Amazon and with free shipping, convenience and peace of mind.
Wonderful little thing - feels solid, has a satisfying, deep click and a firm scroll-wheel. For an idea of size, it fits snuggly into the touchpad area of my Samsung notebook. Not too small that you go clawhanded with just a few hours' usage, but nice and compact, and perfect for travelling. Quite sensitive, though speed is modified with the enthusiasm of your sweeps. Feels smooth. I'm running Windows 7, and when I plugged in the "nano-tranceiver" (thing that receives signals from the mouse and passes them to the computer), it worked in a few seconds, without my intervention.
The nano-tranceiver itself is connected via USB and is TINY! It's a tiny little blob on the end of the USB connector, and has a small slot right next to the battery, encased in the same compartment. Excellent.
The mouse has an on/off switch underneath so's you can conserve battery - great for the notebook/ laptop user.
Takes 1 AA battery (included) which is said to last for up to 10 months.
Excellent value for money. Great product.