Useful, despite the fact that this might be one of the more ill-timed investment books of the second half of the 20th Century. [The only book I can think of that was more ill-timed? The Gorilla Game by Geoffrey A. Moore, which gave investment advice that would have *crushed* a contemporaneous reader, but would have been valuable in nearly any other market environment.]
Written in 1980, totally bearish in tone and subtext, and released to the public just moments before the great 1980s-1990s bull market in equities (from 1980 to 1999 the DJIA went up an astounding 13-fold), Harry Browne's "Inflation-Proofing Your Investments" is yet another example of how books on investing tend to wrongfoot the reader who reads them when they're released. By the time this book reached the public, inflation stopped being the problem.
Which is why it's surprisingly useful to read investment books "out of their cycle." In today's investing environment, inflation rates are historically low and not many people are thinking or worrying about it as a threat. Perhaps that's a sign.
Written in the 80's, much has changed since: tax laws, CPI algorithms, transparency and integrity of the government, etc. Still, this book is a good overview of different types of investments & many sound strategies can be gleaned.