The Nano includes a high-sensitivity laser, which we found to be quite effective on most surfaces -- except for glass, of course. It is certainly more efficient at tracking than the Logitech V270 Bluetooth Notebook mouse, which we use in the office and is easily stymied by a white table.
It's comfortable to use under most conditions, though the sensor is mounted off-centre, which means it's difficult to use on your knee. The device is also configurable to your taste though the simple but powerful Setpoint drivers. The software even tells you how many days of charge are left on your mouse -- about 170+ with the alkaline batteries included in the package.
There is only one problem with the VX Nano -- its price. The Nano isn't quite as cool as the VX -- which is still our favourite portable mouse -- and with recent price drops it is available for less than AU$100. At a $30 premium, it's difficult to recommend paying extra for VX Nano.
With a whole month till the mouse is available, this pricing could yet be revised, as the VX Nano rightly costs less in the US than its larger counterpart. Still, it's very portable, and the cordless sensor is set-and-forget... but we'd wait t see if the pricing rights itself.