Absolutely dreadful… the original mast in our town (Blackpool) was damaged, O2 never bothered to replace it… most locations in the town i have 1 bar… utterly useless… complained several times and was fobbed off at every turn… last time i raised the issue i was assured someone would get back to me, which they did via text message 5 and a half weeks later saying the problem had been resolved, it most definitely hadn’t been. If i could give a 0 i would.