Its basically a docking station, which you plug any combination of a navigator and/or controller and charge up at the same time.
Its very easy to set up, plugs into your mains (not the PS3 USB port), looks stylish and sits nicely as it has firm grips on the bottom.
Charge time on the navigator is 2 hours, while the controller is 4 hours. Hence loosing one star, as I can see long play times being stopped by batteries running out.
You dont get USB charging cables with either the controller or navigator (but they do use them) and if you already own two normal PS3 controllers which you need to charge up also....
....this can make life easier.