One of the best books on the subject out there. Really takes you through the process of finding an edge in the volatility space and shows you how to profitably trade it. Sinclair is a master of his trade and takes a no-nonsense approach to things. Yes, it's all about making money, but focus on the right process and the results will follow.
Yes, you need a good background in math to gain the most out of this book. As someone with a Master in economics, I was able to follow most of the derivations, though sometimes I also had difficulties understanding everything. I would say that you shouldn't attempt to read this unless you have read Hull before, no matter what your background is. Don't read this book if you just started with options. You need to know BMS, elementary stochastic calculus, and trading practices for this book.
It's true, the book reads like a journal article. However, this is meant in the best way: it's concise, accurate, and with a clever sense of humour when needed. I love Sinclair's writing style. Though, there are typos in the text and equations throughout the book. Nothing that is too damaging to the flow of the text.
I read his Positional Option Trading before this, and I still gained a lot from reading this book. Yes, there are overlapping chapters, mostly the non-mathematical parts, but I would still recommend it to those who read his other stuff.
The list of resources at the end is a gem. I will surely read some of the books listed there.