First I'd like to say I am in no way associated with this book, I just borrowed a copy from my local library.
I think this is probably a GREAT book to read if you're not doing NaPro. Not having done the Napro intro session yet, I am pretty sure the techniques will be taught there. They pretty much say they are the same as NaPro, but without a religious angle - and that may fit better with some people, so if that's you, I encourage you to pick it up at your local library.
It clearly outlines how to chart most effectively, and how to read your charts, what else besides fertile/non-fertile days your charts are telling you. At the very least it renewed my vigor for charting - I use the Ovuview app on my phone, but I had been slacking (it does all that fancy coverline stuff for you). I knew how to chart before, but reading this has refined what I knew - in a good way. :) I'm actually looking forward to charting my next full cycle!
It has a chapter on fertility and night-lighting, which is the whole reason I got the book out in the first place. That was certainly informative, but I would have preferred a little more detail. Like - would it be better to try and line up with the full moon? How would one go about that? I was speaking about this with my Aunt yesterday, and she mentioned she knew your cycle lined up with the moon because back-to-the-land-dykes (her words, not mine) had told her so - and apparently it doesn't take too long to switch? I have another book coming which further expounds on this 'night lighting is screwing us all up' theme.
There is even a section on healing child loss, which I skipped, but I think is great to include in a book about charting and TTC/preventing pregnancy.
They do go on a bit about fertility and food, and she is a huge fan of the Weston Price style of healthy eating - which I have to admit, I think makes a lot of sense. Her suggestions are pretty general, and as an IF veteran it wasn't new to me (gosh, transfats are bad? You don't say!), but having an extra reminder never hurts.
In general, I think this sort of book is good - it is all about taking charge of your own fertility, and not necessarily relying on what others tell you. What are you waiting for? Go borrow it! :)