Anecdote
After failing to join Tiscali for three months (they've never said what was wrong, and they still owe me my connection fees) I eventually went for Talk Talk.
As stated by Jess, the connection time is loooooong (3 weeks) when you've no other means of getting the 'net at home, but the service has been top-notch other than that.
The AC was right about slow connections during peak times (weekday evenings and weekends), but it feels like an active throttle to me - literally goes from 250Kbps to 60Kbps within 5 minutes of 5pm during the week.
Other than that, I'm damned happy with it - especially for £17pm ;)
Shame the ISP game is collapsing, though. Feel like the mid-90s all over again