The only problems I have ever had where due to BT screwing up my line when I signed up!
I am on the business 1 pack (up to 8MB/s a second - getting about 3.5/4MB/s.
Always stable and always on when ever I need it!!
They do not block ANY ports (like some ISP's) and offer free multiple IP's even on the home packs!
On the business pack i am on, they don't complain about my over 100gb a month download usage (legal downloads/file transfer to and from work networks (2 of them - and the files can be HUGE (1Gb a time sometimes!)) Oh, and I downloaded Office 2007 (RC1 and RC1TC1) and Windows Vista Beta 1 and Beta 2 (some very large downloads there LOL). I also download *NIX iso's for myself and friends - Also running a Windows 2003 file server from home (so I can listen to my music collection at work and get my files). All this adds up to huge usage that they do not and have not yet complained about!
I have been with them for about 15 months now - and can't see my self moving to another provider (even free ones that would get me free phone stuff)
You can regrade your pack online 24/7 and the online control panel is very easy to use.
The only other stuff I could say is - BUY! If you go for a 1 month rolling contract there are NO cancelation fees - though you will have to pay an install fee (catch 22 situation - if you know you can live with them for 12 months (and you can) I would advise to go for the 12 month contract).
Oh, and there customer service is BRILLIANT (remember though - im on a business pack - so better level of service then home). I would think though, there service for home users will be just as good! When ever I have asked a question (email) i get an answer the same day!
Anyway, I could go on about Eclipse all day (and have done to other people before - I can be a bore sometimes LOL) so I will stop now!
Any more info - lemme know!