I've read a few screenplay books and this one may be one of the best, plus it's a fairly recent publication, which counts for something, even though the screenplay craft hasn't changed much in decades. This book provides numerous tips on how to write a screenplay somebody may actually want to buy. It shows numerous references to actual movies, explaining key points in great detail. Be that as it may, it didn't cover absolutely everything I've read about screenplay development, so I definitely wouldn't call it a "complete book of screenwriting." But you wouldn't need such a book anyway. If you don't have enough talent, time and motivation to write and market a screenplay, no screenplay book, complete or otherwise will be enough.