I'll head off and give it a go

Just to add an extra bit of info - this seems to be pretty much a permanent promotion. When I did took advantage of it about a year ago I found at least ten sites linking to similar offers but they weren't all the same, some offered one book and some two. I signed up for two books, downloaded them and cancelled my subscription. I got my books and nothing was charged to my credit card. It was such a good experience that if I decided I wanted any more of their books, I would have no hesitation in re-signing and paying the money.