You can dabble in a lot of sports, but in real, hard core strength training where you want to see results, you've got to be all in. Dan John is completely committed. He strips away nonsense and provides extremely simple workouts. The only thing is, you've got to do them.
The book is a series of musings (likely collected blog posts); it doesn't cite studies (although he credits other authors and coaches for their ideas), doesn't discuss progressions or much cross training, and is not sport-specific. Dan provides detailed information about the benefits of swings and loaded carries, which haven't been covered in other books I've read so far. I also liked that Olympic weightlifting features centrally in Dan John's training programs.
The author makes some wonderful points about fat loss, mass and strength building, quality sleep, and getting focused on improvement. The weights he suggests are aimed at a high school or college football player, but if you can't manage them (and no way can I do a bodyweight snatch or bench press!), the same basic principle applies - just do what is intense enough for you to see changes. The book is also very funny. I highlighted quite a few gems for later reference, and I will certainly read more from Dan John.