I can't comment on their fancy cable / fibre optic stuff, as we haven't got it near us. However, as far as their 'standard' copper wire 8MB ADSL Max service goes, I left when the daily evening speed drop (6.00pm) took me down to a 36k connection. My dial-up modem was faster.
When you got through to their so-called support, they were indeed dog-do. Told me it was my equipment, that it was my browser cache that was causing it etc, etc. Usual dork somewhere on the other side of the world reading from a list, probably. One person actually told me that I had complained too much about the problem. Yikes! Eventually, one supervisor phoned back, apologised, admitted that it was a problem at their end, and said that I'd be better on a fixed speed service - at the same price.
So I left and moved to ADSL24. Speeds are up to their previous highs of 4-5MB, and only drop after 10pm, but usually no lower than 2-3MB. When you phone them, you get a real person in the UK who can actually do something for you.
I had the last laugh in Virgin when they cocked up my final DD payment, that they shouldn't have taken. I found an 0800 number for them and after being bounced around a few operators, got things sorted - it took over an hour on the phone but at least I didn't pay for the privilege!
Andy