I have had good service from both BT and Sky, decent speeds and good support when required, the app for WiFi is a bit poo, but it does work most of the time it just tends to find and connect to the BT-Fon, Openzine, BT-wifi hotspots first even if your home network is in range and you have to force connection to your own faster connection. Apart from that my infinity service has been fine and fast for 2 years and far outstrips the supposed equivalent Virgin fibre connection we have at the office on our development network.
Carl.