Absolutely terrible ISP. Because they don't use traffic shaping and our area is massively over-subscribed, around 5pm-1/2am every day, I go from having 12-14mb to around 1-3mb! The whole network just jams up! iplayer, 4od and youtube are pretty much out of the question at these times.
They also refuse to accept that the problem is Sky's and tell me that my computers have viruses (not a chance!) that causes this! I only found out the cause of my issue because Sky admitted that over-subscribing in *a few* areas was an issue, on the news a few weeks back.
My advice is ... found out how many people in your area use Sky broadband. The best way to tell is to see how many Sky wireless routers are in range. If there are a lot, don't bother!