So, I promised a review of this, but it too me a while to work through to it in my giant reading pile.
For me, this book was a watershed. For years, I have been trying to improve my observation of the world around me, with limited success. This book has bumped me to the next level, as it has tied in with prior reading (indeed the author's previous book was one piece of this reading, but it wasn't that prior book that led me to grok it!) and some observational and tracking training I have had, and just helped it all gel.
Don't get me wrong, I still have a huge distance to go with this, but this book has pushed me a good way forward and just made the world a more interesting place for me.
If you are receptive, and ready for it, I think this book can literally open your eyes to things in the world that you may have been missing everyday. It teaches you to really look at the environment you are in and truly notice it, to spot the clues all about you, make connections from them, and extrapolate something that was there to be found but was hidden. You can use these techniques to find direction, or to discern the habits of things around you, or see into the past of the place you are in.
You will truly notice the blowing of the wind, the movement of clouds, the way the grass has bent in a paddock, how certain trees look like they have been lifting weights, or how another tree is tall when it should be short. You will hear the different calls of birds, see how moss has grown in some places but not others, notice how one part of a street is just a little more worn than the the rest, wonder (and answer) what ivy and other vines are reaching for, and many other things. You will start to notice where water has puddled, ants have made their nest, and perhaps perceive some of what has shaped the land you walk upon. Tracks and trails will start to jump out at you. You may even realise where it would be best to go to get a photograph of a rainbow at sunset. Better still, you will notice all this and begin to perceive what story it is telling you about the place you are in! It is all quite marvelous!
Some people can already do all that - I wager many on this forum are already very accomplished in this area. But I was not. I couldn't even begin to do it. I had many of the bits, but couldn't put them together. Now I can, reasonably well. Maybe I can begin now.
To be helpful to other less aware folk like myself, let me suggest to you some traps I have noticed and that you can perhaps avoid if I point them out - for this to work, you must walk with an open and questioning mind, seeing all there is to see and all the clues offered. You must take all your environment in, and not tunnel your attention or observations on specific things for very long(e.g. trying to find direction from the clouds, or even trying to find direction from multiple sources, or studying only the plants around you) lest you miss other clues. The trick is not to seek direction (or whatever), but discover it if it is there to be found. Prioritise perhaps, but let your attention move around.
You must also never seek something to support an assumption you have (or you will find it, but it will likely be wrong), but must see what is really there.
You must also notice when things change. Do not rest upon your laurels. This kind of information is usually highly situational and the clues will change as you move, and you must notice them change as they do.
Lastly, and this is the hardest thing, you must keep practicing every day because as soon as you forget and allow your attention to turn only inwards, then your eyes will close and your mind go to sleep, and you will once again start to miss the world around you.
P.S. It's not a trap, but FYI, this book is written for the northern hemisphere, specifically for the UK walker, and some specific facts and scenarios listed in the book do not apply elsewhere (but a variation may well apply, if you think it through. Do not try to rote learn signs and clues).