I finished "Of Dice and Men" a few weeks ago. I enjoyed learning about the back story of D&D and TSR. Its principle failing is in the lack of discussion of the Open Source release and the resulting blossoming of clones. I think any truly objective discussion of D&D's history must include the release of the SRD and all that grew from it. Pathfinder is currently the major path for D20 enthusiasts. Its success is a strong indictment of the mistakes made by TSR/WoC, their misreading of the desires of its base of support, and is a model for how to create a sustainable RPG enterprise. The book's final chapters read as more of a commercial for D&D 5e than anything else.
That said, I am glad I read the book. The early history is worth the read.