From the inside flap - "REWORK shows you a better, faster, easier way to succeed in business. Read it and you’ll know why plans are actually harmful, why you don’t need outside investors, and why you’re better off ignoring the competition."
Note that the claim is not 'Rework shows you a better, faster, easier way to succeed in a business that is similar to 37 signals. Maybe'.
No doubt. But what the what the OP is trying to do is weasel away from a critique of the book by saying 'Well, it's really mostly about 37 signals. If you don't like it/doesn't work for you, well, that's just, like, your opinion, man'. I imagine you wrote the book with the notion that it is broadly (not universally) applicable, just like most books in the genre. And it's perfectly sensible to review it in those terms, just like this and all other reviews I've seen so far have.
The fact that an italian cooking book tells you that after you read it "you'll be able to cook amazing meals" doesn't mean you'll be able to cook amazing "thai" meals... It also doesn't mean that if you can mix things up and come up with food that you like better, it isn't good food.