Well, people have been unable to settle on a comprehensive definition of happiness in the few thousand years the argument has been documented so I don't think we'll settle it here. But consider that we identify so many kinds of happiness, from the fleeting to the unforgettable: joy, euphoria, satisfaction, ecstasy, etc. I think Brave New World is about excluding all else in life but one of those. If that sounds good to you, go for it! No one can tell you what happiness is — except that's exactly what the authorities in Brave New World are doing, and they are eliminating the option of pursuing other, perhaps greater happinesses than the one they have chosen for you.