I am on O2, all is well on this end. I have a mobile so am paying £7.50 a month for 8 Meg Broadband along with my £15 a month Sim. All in all, great service and good VFM on all fronts!
ants83 are you existing customer or did you get new mobile phone contract in order to get the broadband service?
Also can you get upto 24mbit instead of 8mbit but at cheaper price?