I used to use them all the time. At some jobs, we would have a library of phone books for cities all over the country and major business and manufacturing centers worldwide. In the last decade or two, however, what used to be given for free on request has become difficult to obtain and not free. What had been one local directory comprising white pages and yellow pages has fragmented into half a dozen or more of each--published by different companies interested mainly in advertising revenue--none of which has anything like complete coverage. Further, the so-called "smart" yellow pages only serve to make things harder (or impossible) to find.
I still use printed phone directories and yellow pages occasionally for local stuff, but it's generally much more efficient today just to Google whatever you're looking for and to maintain a custom set of bookmarks for things you'll be wanting to look up regularly.