I now have it for a few days. It really helps having an Apple store in town to get the latest releases :)

It is reasonably big, the usable surface is almost as deep as the Apple USB keyboard so gives it a surface area similar to usable area of a mouse pad. It feels more like a mouse a mouse to use to the large surface area, making it more intuitive than a normal laptop trackpad. The glass surface also feels smooth and makes it easy for the fingers to slide on top.

What really impresses is the gestures and after you get used to them you cannot go back, specially the 2 finger scroll with inertia.

On the minus side it does not work with PPC Macs, it needs Snow Leopard :-( It is also rather pricey at £60. The Bamboo looks like a better proposition but it does not do as many gestures and is even more pricey. I Already have a Graphire 2 so it was less of a concern for me. 

As it is on my desk and the fact that it does not move the bluetooth does not stand out but I can see it being rather useful on the Mac Mini when plugged under the TV.

Ah, it comes with batteries included and ready to use.