I have been with Merula for over 5 years. I have always found them to be superb at tailoring packages to your individual needs. I have also found, as a home user, that they have always kept their word and tried hard to sort any problems with tenacity and eventual success. They are not the cheapest but I recommend them to my friends because I know if there are problems, they will be solved by a UK based engineer. The only criticism I have is that their admin can be a bit flakey at times. But with their recent expansion into new premises, this should improve.
If you want reliable ADSL with excellent support, then Merula are an excellent choice!
John