We bought this Lenovo as a controller for our Nettop through which we watch UK TV.
It communicates to the Nettop via a dongle which seems to have a good detection range, not only by distance but also from the angle at which you point the keyboard.
The Lenovo is basically hand sized, so yes the keyboard itself is small and you wouldn't really want to write a lengthy e-mail using it, but as a controller, or for typing a few words in a 'Google search' it is ideal.
The roller ball is loose and is very sensitive. It doesn't take much to make it whizz unintentionally from one side of the screen to the other, but like most things once you mastered how to use it, it is fine.
The rollerball also seems sensitive to moisture.... ie damp hands or atmosphere.... the rollerball then does not control the on screen cursor, but once dried out it resumes and works properly again.
We like it, it serves the purpose for which we bought it, namely a wireless controller to change the screen on our TV from the comfort of our settee, and looks good with the other items we have. (ie Lenovo Nettop)