Excellent product, which we're using inside our old granite-built house, since a recent broadband problem means we have to plug everything into the BT master socket, which is in one corner of the house on the first floor. That meant we had a poor signal in the opposite end of the house on the ground floor.
At first, I tried using the HomePlug with the surge protectors, since we occasionally get lightning strikes which would destroy our electronic equipment. The Homeplug does not work if plugged into a surge protector, so make sure you plug it directly into a main socket, and be prepared to run around and unplug them if a thunderstorm is brewing!
We also have one plugged into our log cabin/office which is 70m from the main house and router. I'm writing this review from that office, revelling in the fact that broadband works just as quickly via the electricity supply out here as it does sitting right next to the master socket in the house.
Just about to order two more - I'm really impressed, so 5 stars!