I switched recently to BT everything because I wanted one box, and one bill, and where I live only BT can do it.
There is no HD currently unless a movie that you download. I can't get ESPN or Sky sports due to signal weakness. The BT Vision system is very confusing and slow to use, and at first I thought the lack of choice of kids stuff would cause a riot...
However! It works out about half the price of the equivalent Sky+ package plus BT phone + Virgin broadband that we were on, and the kids hardly notice, and possibly actually watch less TV which is no bad thing. The Sports thing annoys my son but he has plenty to watch really. We love the record/pause live TV thing which we would have to get Sky plus for at questionable levels of expense - we don't watch that much TV but we like to watch the programmes we do like, at a time that suits us.
I don't think we'll be on the infinity service for a while, we don't officially get Freeview for another 2 years!!!
I kept the Sky box for Freesat channels,it has to be said the picture quality of normal Sky is dreadful, but it has been suggested that this has been done on purpose to exaggerate how good HD is. Our non-HD BT is much better than Sky, although there have been occasional signal problems and flickering.
In a two year deal and a couple of months ago I was getting irritated by BT, but it is growing on me.