No such thing as really free within a broadband service. Charges are obtained via the 'extras', so it pays to fully understand the commitments before signing-up. You may have noticed, that the usual 12 month contracts have in some cases been extended to 18 months. A long time if things do not go to plan!.
If you follow the forum, you may have already noticed certain problems have started to appear with some of these 'free' offers, due to perhaps over subscription.