I read this book some time ago and as well as re-emphasizing some of the things I already knew about PHP security, it certainly brought a few finer points to my attention.
While the book is quite small at little over a hundred pages, what you get is pure. There's no sidetracking onto this and that, this book is targeted one hundred percent at PHP development.
I'm no book expert, but I would definitely recommend this book to aspiring PHP developers and think it would also benefit some of the more experienced folk out there.