The book content is good however there was a good 15 pages missing in one of the 6 books. Not sure how many more of the books have the same issue. Customer support says return policy is only 10 days. Which means you need to check all the pages in all the 6 books in 10 days to be safe. Alas I did not foresee such a problem. In this digital age a practical solution is for Cengage to just send a pdf of the missing pages.