One of the aspects of Huxley's World State that I found the most amusing was the idea that happiness is the end-all, be-all design of this futuristic society. Not meaning to tell a pun here, but unhappiness was frowned upon! Anytime anyone got the least bit down, they were encouraged to pop a soma, a drug that induced a feeling of immediate euphoria.
The book's main protagonist, John the Savage, rebelled against perpetual happiness by, among other things, whipping himself with a knotted cord. While I certainly wouldn't encourage folks to take such extreme measures, I think that John had the right idea.
For one thing, as Lao Tzu likes to point out, happiness holds no substantive meaning without unhappiness. This represents one of the reasons that the Christian version of heaven makes no sense to me. How could a person experience genuine happiness or love without real unhappiness or hate to judge it against?
For another thing, unhappiness and discontent are great motivators to spur us to improve our lives and/or our attitudes. While I believe there is no question that we can learn valuable lessons from our successes in life, the same is just as true, if not more, from our many mistakes and missteps. When we screw up royally -- which often causes unhappiness -- the sagacious individual learns not to replicate the screw up again.
Besides, I think happiness is overrated. It tends to be ephemeral and, like a drug, many people will try anything to get back the happiness high and many of the things they try lead them (or others around them) in the opposite direction!
I'd much rather be content than happy.