Which? has published its survey results on Broadband.
In its Best Buy Guide section, it has this to say about NTL:
Don't buy
NTL was one of the worst broadband providers in last year’s survey and was also rated well below average on every point this time.
It adds, later in the report,
NTL has the unique distinction of being well below average for all our ratings. Steer clear.
I had enormous problems with NTL last year - including a week's loss of service, but so far this year it's been OK.