I don't think the book needed to be as long as it is. There is good advice to be found, but it drags on and on feeling like a "deep work" session in of itself. I was often waiting for it to "get to the good part" in each chapter.
I also think this book is tailored toward someone who can afford to do these "deep work" sessions, but not everyone has that luxury. Seriously, expecting everyone to have the ability to lock yourself away all day without distractions? That's a tad unrealistic for most people.
The book did help identify areas where I often engage in shallow work, and I like the idea of bundling that work together in one large go to work through it quickly.