Burkeman has a difficult story to tell. How do you achieve happiness by reading a book full of "unhappy" (=realistic) insights? What should you actually do?
The author concludes with the observation that any "x-points to follow be happy and successful" is very ill-fitting, or better: totally besides the point of the book. It means that many people, looking for pre-chewed chunks of advice, will throw the book aside. Burkeman's message is: there is no plan, there is no "success list". But those who try to incorporate reality into their lives, especially the negatives and the failures, are better equipped to handle their lives and will find happiness more easy.
The message of the book is not: be pessimistic. It's: be realistic. Observe the negatives and the failures, describe them, calculate what they will mean for you and incorporate them in your life.
Burkeman builds his story by going step by step through history in a non-linear way, from Stoics, via meditation to the Mexican celebration of Memento Mori. Sometimes the story is a bit irritating when the author states over and over again that "it's hard to believe, but..." That's really not necessary. It almost looks as he tries to apologize for the fact that the world is different than the "if-you-want-it-you'll-succeed" prophets tell you. There's enough (scientifically solid) research in the book to let the reader see that the real story to feeling happy and positive is quite different than we are led to believe.
This book is a great antidote for the "positive thinking books" which are way too loud. But it's also a great addition to them. What I like is that Burkeman closes with the story of his own use (and results) of the knowledge he has gathered.
But again, it is not a self-help manual. The reader has to start working with the content him- or herself, without a program from the author.
And that is good.