We have it. It's OK, the box is straightforward to use and reliable. In terms of the channels available, it's basically Freeview with a couple of extra bells and whistles. Don't think I've ever paid for any of the extra on-demand stuff, but I'm a cheapskate.
I only have the sports package, well, ESPN. Don't know if I'll be forking out the extra for Sky sports on it, since Sky are squirrelling away the Scottish fitba I want to watch on channels other than Sky sports 1 and 2, which are the only 2 BT Vision will be carrying. If all you want Sky for is the English Premier League, you should be OK because I think Sky are obliged to show most of the games from that on Sky sports 1 and 2. Doesn't do any HD channels.