I've been using Citifeed Plus for many years now. The service has always been pretty good although frustratingly there used to be some nights when the file wasn't there to download (i.e. you found you'd downloaded the previous nights data). This particular prob hasn't happened for a while.
Since moving the download site from a bulletin board to internet only I'd say theservice has actually improved. I use Metaload prog to download the data. I have to say I haven't used any other data provider so have nothing to compare Citifeed to. Plenty of data formats provided, Metastock, AIQ etc.
Please note: Haven't tried customer support so can't comment on that though the Review makes me put a rating in.
Reliable service, never had any problems in 5 years of use but contacting them is easy and they are happy to answer any questions. Cost is £105 per year for all UK shares with OHLCV data. You will need some software to download and update your data, such as Metaload.