I just checked, and they did quote 17 pages (they included the inside back cover for that extra one), so it's entirely my fault. The 'Book' two doesn't seem to have any number of pages stated, another in the series has 33 pages, and yet another 25 pages.
As I said earlier, I like the concept, I am just questioning the description of 'book'. Booklet or pamphlet would have been a more accurate description in my opinion.
As it is, several of the 'books' I have bought recently have less pages than the average quilt magazine, but cost up to four times more.