http://www.three.co.uk/Discover/Built_for_internetting (you can check here if your area has been upgraded for the new speeds)
They are to cover 50% of the UK by Christmas 2012 with speeds of up to 42Mbps
Here is a speedtest from back in September showing speeds of almost 20Mb:
http://www.speedtest.net/iphone/329516475.png
And another one:
http://i235.photobucket.com/albums/e...2-20-42-01.png
Why people wish to pay ee on their overpriced network when you're not getting much more and having to pay so much more, plus Three have truly unlimited data plans which is another plus.