In the pantheon of endgame writers, John Nunn certainly has a distinguished place. Beyond his immense skill as a chess writer, Nunn's love for technology has allowed him to bring endgame writing into the computer age. While in some cases this has led to the esoteric--his wonderful if not a little impractical Secrets of Pawnless Endings being a prime example--he has also used his powers for good, mostly recently in Gambit Publishing's Understanding Chess Endgames.
The book might better be called 100 Endgame Themes John Nunn Thinks You Should Know. An offshoot of a (planned?) larger book on endings, Understanding Chess Endgames is a collection of essential endgame themes that features Nunn's usual mix of clear writing and laser precision. The layout is a little strange; in the introduction Nunn even suggests that the best way to read his book is "sections 1-15, then a glance at sections 76 and 77, back to section 16 and then straight on for the rest of the book." Seems odd, but I'm not going to argue.
As with all endgame manuals I read, my personal preference shapes my enjoyment of the material. The coverage of bishop endings was useful, but a bit dry. In contrast, my love for the weirdness of knight endings meant I particularly enjoyed that section. The section on rook endings isn't much different from what you'll get elsewhere, but the introduction to that section does tie everything together nicely. Also, the discussion of tactics at the end of the book was fun.
Nunn stresses that his book is about instruction and is not an encyclopedia. I agree. If you want complete coverage, consult Lamprecht and Muller. But that is what's refreshing about Understanding Chess Endgames. It straddles a weird space on the spectrum ranging from the traditionally linear and engaging instructional manual like Yasser Seirawan's Winning Chess Endgames to the mind-numbingly thorough Basic Chess Endings. Understanding Chess Endgames isn't a book that you're going to read in bed, but it also isn't one that's going to go down like cough syrup (my apologies to Mr. Fine). If the strength of Mr. Nunn's previous work alone doesn't get you to check out this book, consider my endorsement the clincher.