I find it strange how most of the criticisms of this book (and other LP's) center around LP's alleged inability to capture Turkish culture as accurately as people would like. I've got a crazy idea for these critics -- YOU CAN'T EXPERIENCE CULTURE FROM A BOOK!!!
This book, and most LPs, are good at doing one thing: orienting you. That means giving you the basic facts to get to a country, get situated (sleep and eat safely), and figure out where to travel (itinerary planning, and their maps are the best). The rest is up to the traveler. As such, I take LP's cultural experiences and observations with several grains of salt. In other words, I use it as a 'guide', not as a mandate.
My wife and I just got back from 3 weeks in Turkey, and had a fantastic time. LP helped us plot our course before the trip and figure out places to stay along the way. Once in Turkey, we relied more on a friend of ours who owns a travel agency in Istanbul, but LP helped with some hotel recommendations and restaurants when we were too lazy to explore or had limited time in a place.
In terms of social mores, we used our own judgement, with a little help from LP, and never had a single problem anywhere in the country. Yes, she covered up when we went to mosques (out of respect); on Istiklal Caddessi in Istanbul we could dress more Western and get away with it. These kinds of things are best learned from experience and from the people, not from a book. Put another way, the book can tell you absolutely what *not* to do; as for what to do...that's the fun of traveling, isn't it?
All in all, even if we had had a horrendous experience in Turkey (not possible, in my opinion -- I am a Turkophile through and through), I wouldn't presume to blame LP. I have used them for India, all the countries in Europe, Morocco, and South Africa, and they have never steered me wrong -- they're great at helping you with your first steps in a new country; after that, the journey is up to you.