My recent experience is that speeds are a bit variable, though I couldn't honestly say they've been disastrous.
My contract with Plusnet promises "up to 8Mbs" download speed, which is normally reckoned to mean
about 6Mbs in practice, I think.
I ran a test at 2 p.m. this afternoon and got a downlaod speed of 5.9 Mbs, which is pretty respectable.
By 5.15 pm., the download speed had dropped to 4 Mbs, still by no means disastrous - and almost certainly
slower because people were getting home from work and school and logging on, thereby creating more traffic on the system.
Others don't seem to have been so lucky, I appreciate that - but I think it's quite important if we're to approach BT et al
that we have some concrete figures on download speeds to report, especially at peak times.
You can get a speed reading quite easily from this website: http://www.mybroadbandspeed.co.uk/