I only went for it because of the awesome cashback offer. After waiting 3 months I put in a claim which was denied and then got re-opened as the 'denial was a mistake'. So I waited another 3 months and this time it got denied for real.
Unbelievable. So I now have a 12 month contract with sky tv and broadband but no cashback, even though I have all the documents as proof.
If you're only getting this because it seems like great cashback - maybe you should rethink.