Since Aldous Huxley's Brave New World Revisited is essentially a justification of the original novel, Brave New World, the value of reading it extend from the value of reading the original text. Indeed, there are valuable lessions that extend from Huxley's novels:
Technology and science can desensitize and dehumanize people.
In Huxley's dystopia, the use of such things as hypnopaedic conditioning programs the people to have certain attitudes towards other castes, death, nature, etc. Soma desensitizes people to anything that might disturb their contentment with their society. Entertainment machines generate innocuous leisure and prevent people from delving into truths or issues that may be disturbing to them. They do not talk to one another individually, interacting in a normal social manner; nor do they enjoy and appreciate nature.
The effort to maintain the people's happiness prevents them from exposure to the truth
The government makes life decisions for the people of the New World; the State censors books and religion because the truths found in these realms may upset the State's control. For, it is only when people are not content, or when they learn the truth about governmental control that people revolt or disagree with the status quo. The all-powerful government of the New World with its World Controllers keeps people in a state of self-delusion. If anyone demurs, he or she is banished from society lest he/she disturb the peace.
In the last chapters of Brave New World, John the Savage says he want disease, he wants sin, he wants unhappiness. For, he knows that without these miseries, one is not truly human. In order to attain truth and real happiness, one must know sorrow.