Just a quick note: National Geographic is no longer publishing the annual index. Instead, they have an index freely available at http://publicationsindex.nationalgeographic.com. It is keyword searchable, and very easy to use.
I'm not a huge fan of dusty old reference tomes that are hidden away in a separate reference collection, little used, largely overlooked, and forgotten. I did, however, like THIS particular reference book! I have found it very useful in helping patrons use our National Geographic back issues...and we have a LOT of them (back to the early 1980s, I think).
I'm happy to see the new FREE online index, though, and accept it wholeheartedly as a replacement for the print volume.