If you travel, and you hate to have the lump of a mouse in your briefcase or bag...this is the answer. It folds so flat that you can barely notice it in your bag, the reciever is so small that you never need to remove it, and it works very, very well as a mouse to boot.
Having said that - it's just incredibly COOL. The articulation of the folding mechanism is something that 20 years ago would have been science fiction. The touchpad works very well also, and the fake "click click click" as you scroll via the touchpad is a nice touch. It also tracks on reflective white desktops that few other mice will.
Really, it's a great product - everyone in my office went "OOOH" when I unwrapped it and demoed it. Your opinion of MS software should not cloud you from admiring their hardware...having said that, the worst thing about this is that it only works on Windows, not Mac.