Frey’s advice is derived from Aristotle’s Poetics, the main source for most writing instruction, so you can’t go far wrong following his advice. Frey emphasizes building well-motivated characters, who encounter and deal with conflict, leading to a climax. If you didn’t know that’s how it’s done, then this is the book for you.
His discussion of a story’s premise (the “moral” or point of the story) was helpful, but I often disagreed with his examples. “…Lolita proves that ‘great love leads to death.’” Really? That’s not how I read it. In fact, that seems a million miles off base to me. Several examples like that made me question the reliability of the book.
There isn’t much discussion of the nuts and bolts of writing, such as choosing the point of view (which Frey annoyingly calls the “viewpoint”). The chapter on writing good dialog made a useful distinction between direct and indirect dialog, but the examples of indirect were smart-alec tough-guy talk from a cheesy detective novel, not helpful. Something from James Agee or David Mamet would have served better. The section on rewriting and editing was weak.
Overall then, if you are a raw beginner, this book will get you on your feet and pointed in the right direction. Otherwise, even though the book is an international bestseller, I’d say look elsewhere.