This book is a deep exploration into society when it is run at maximum efficiency, diving into Marxist theory such as social stratification and social mobility while the people of the World State are suppressed.
This vision of society presented to us by Huxley shows a world where nothing is questioned and everything is conformed to the will of the state. This sense of unity through controlling is integral to the structure of the World State, and Huxley presents the various mediums through which this can be seen, such as Soma, the conditioning of the classes, etc.
Personally, I think this novel did a phenomenal job of presenting a utopian structure within which dystopian norms arose and eventually became staples of the everyday lives of the citizens of the World State.
Overall, Brave New World is a great read to dive into the complexities of society and how structure and classes differ from what is presented on paper versus the actual application.