I have had Sky BB for over a year now. I pay £5 per month for up to 8mb. I generally get 5.5mb actual speed but like all providers it varies.
Had teething probs at the start but was sorted and had no problems for a long time.(Except when my firefox tabs were saying "problem cannot load site" but this turned out to be ZoneAlarm mucking about. Deleted ZA and now all ok).
For the cost I would recommend it.