Its the overall package which has attracted me, we currently have Sky inc sports mainly for F1.
I believe from memory our current package with Sky is 500mbit broadband, Sky TV inc sports and an additional multiroom box for approx. £85 per month.
Virgin offer the Ultimate bundle which is gigabit broadband, full TV package inc an additional box including BT sports and an unlimited data sim card for £85 per month. I assume there is also the usual £100ish or so cashback to be had via Quidco or similar. I'll have to see what, if any retention offers Sky come back with but I image they will be hard pushed to top Virgin's overall price vs package.