Wow, Margin of Safety must have elevated itself over the years to cult-like status. It was written in 1991 and has been out of print for many years. Prices for used copies reach into the stratosphere. The copies currently available at Amazon start at $1,494.99. With the book being so expensive, there's no chance at all that I will read it, but I took a quick look at the reviews posted on Amazon. Nobody seemed to have much critical to say about the book, but the negative or less than enthusiastic reviews said it was a fairly basic book about value investing, and that there were as good or better books on value investing that can be purchased at a tiny fraction of the cost.
IMHO, any true value investor should have much the same reaction - you should be looking for underappreciated books whose price doesn't fully reflect their value to the investor, not a book that covers the same ground at 100 times the cost.