I've had a look at the Experian website and it certainly doesn't strike me as the most open and transparent of processes - no indication anywhere of costs after the free year or for retail customers wishing to sign up - always a concern in my opinion. An internet search suggests the US version costs $16 per month for consumers (presumably BA get a significant discount). Online reviews are really very poor (and I acknowledge that these are often biased towards those who are unhappy but these are spectacularly poor). I note the comment above that credit card numbers are taken purely to identify you but also note reviews that auto-renewal has taken place after similar arrangements to those made by BA and proven very difficult to cancel.
Currently I feel inclined to wait and see rather than jump at the offer.