This is a very simple kit - literally swap out your existing battery supply line with this and you are now running your lights on USB power - run it from a computer, a TV or just a plain phone charger.
The kit allows you to connect up to five other kits (but oddly is only supplied with four 50cm connection leads). In my case, I'm lighting up Santa's Workshop, the Toy Shop, The Winter Village Train Station and the bus from the Winter Village Train Station, leaving one free output.
I have my Christmas tree and surrounding setup connected to a timer, so each night everything turns on automatically and then turns off by itself later in the evening.
Aside from only getting four leads, I'd have liked the USB lead itself to have been longer (eg: a standard 1.5m lead would have been nice, especially for the price) - you're forced to add a USB extension if you want to light sets up that are a distance away from the wall charger.
Overall, definitely recommended if you have several Lego sets lit with LMB kits and you don't want to have to keep changing batteries!