Had the 600k service in for over a year with only one problem - the registration server crashed halfway through signup. Called customer services & explained the problem - they said they would get back to me. Three hours later got a phone call that the server was fixed & would I care to try again. Since then no problems.
It might help that I am less than 1 mile from the South Manchester facility and may be less prone to problems than other users.
600k is more than enough. I have to download DB2 iso images from IBM - >120MB - and have no problems doing so. Also downloaded >1.8G Linux operating system with all bells & whistles - freely available from Mandrake, RedHat etc - with no problems.
The frustrating bit is when you need a file and the distant server putters along at 3k3 instead of my regular 75 - 80K.
The TV service - not got a clue, that is for the rest of the family. Not enough hours in the day to work, play and watch tv.
One last point. Very occasionally I notice that the status led on my router - 3 pc's hooked to the system - fails to illuminate. This is because the NTL box locks up. Turn off at mains, slow count to 10, turn on at mains then 30 seconds later back to full speed. I've had to do this 3 or 4 times over the past year.