I got one of these Microsoft Arc mice this weekend. Paid R500. Just price-wise it's cheaper than most notebook/portable mice out there. Most are more than R500. So price-wise it's pretty good.
In terms of functionality, I previously had a corded mouse which I used while travelling with my laptop and it got lost. Then I used a standard microsoft wireless mouse, I like the microsoft form factor of their standard mice but didn't like the huge receiver. That was a problem for me. I got this arc mouse on impulse after seeing it in a shop and bought it.
It does look strange and I was skeptical that it would feel 'good' but it does. It's accurate, light and obviously portable as the little receiver magnetically snaps onto the underside of the mouse. The receiver might not be as small as some of the logitech ones but it's small. It's size is about two lenghts of the metal usb plug.
It feels like a full sized mouse in the hard and as I said works very well. It's a laser based mouse, I had assumed it was a optical mouse initially. The only thing that takes getting used to is that your pink finger 'hangs' over the mouse or can want to go under it. You pinky usually just rests on the 'hips' of a mouse, because this mouse is 'hollow' itdoesn't rest as it would usually. Other than that which one get's quickly used to it's a great mouse, you can just fold it pup it in your pocket if you need to go.
I highly rate this mouse as a notebook mouse because it feels like a full-sized mouse in the had unlike the other notebook mice which feel small in the hand.
If you need a mobile mouse I recommend this one.