Have used it and its very stable and reliable, we lost service only in the worst rain storms with heavy cloud cover. Monthly cost is on a par with direct connect services but the initial equipment purchase is quite expensive (unless you can find something second hand).
Plus point is that you get a UK IP Address so catch up UKTV works well without a proxy - negative point is that there is a data cap on the cheaper services that means you can only watch 20 hours of HD IPTV a month which wouldn't be enough for me and going for an unlimited data package costs a fortune.
In my view you are better off with a PT/MEO package despite the unreliable speed. Especially as they bundle in a landline phone and GSM offering