They work!
I was concerned after hearing of other people getting gift cards for Christmas and the cards didn't work.  I am happy to report that I bought two and both kids reported that they were thrilled with the decision of an Amazon card (one having an Amazon fire and wanting new books and the other a tech nut) and that they were easily redeemed.  Thank you Amazon.  I will not hesitate to buy them again when in need of a gift.  (Oh, and I took advantage of the buy  $50. in gift cards and get a $15. one for you!)  I enjoyed my purchase too!
Rating: 5 stars