I was wrong.
Each of the 52 principles referred to in the subtitle are a 2-4 page micro essay that's more motivational than instructional or reinforcing. I get the impression that it be a good introduction to Allen's principles for reading on an airplane or somewhere else where your time may be limited. It took me a long, long time to get as far into the book as I did.
I couldn't finish the book.
So even though I'm still a fan of the GTD approach to productivity, I can't really recommend Ready for Anything.