Been using 3G connections for a while now and tbh for the most part calling it broadband would be a stretch. Having the ability to place this device in an optimum position without having to worry about trailing wires (well, beyond the mains) has actually turned that around quite significantly.
Can't really say much on the onboard battery as I've not used it away from the mains, but having gone over a few reviews it seems that, as with laptop battery times, the stated 5 hours is in reality much less.
A fairly decent review of the device is
here.
Does seem odd, not having a dongle hanging off of the laptop though.
