I am on a Sky contract for unlimited broadband, line rental and free-to-air tv through my Sky Plus box, after cancelling my full Sky subscription. Cheap at £12.40; the guy swore it was a mistake when I called afterwards but said they would honour it.
Not having any football was driving me mad, but then the BT offer came through email via LFC right before our Champions League group games started. First 6 months free, next 6 months regular price, 12 month contract. Averages out at £13.50 per month for full BT Sport in HD through my Sky box, and skewed for 6 month's time. Felt like a decent deal, and decent timing.
I've actually been quite impressed with the BT coverage; much better than when they first started out. I think with us in the Champions League I would rather have BT Sport than Sky Sports, given a straight choice. European Football, plus FA Cup, and one game on the weekend (which frankly suits me having a young family...I couldn't really get away with 2-3 full games these days anyway) and it's a pretty attractive package.
Sky are right to be worried; finally there is a challenge that really could threaten their model. The next TV coverage contract will be a tightrope walk for them; too much either way and they could be in serious bother.