To frame the effectiveness of feminism in terms of whether it makes women happy is just one more way of patronizing women. It smacks of, "Oh, but the slaves are so well-fed and content on the plantation" or "you'll be so much if it happier simply accepting the status quo rather than challenging it." For example, I might very well be happier than I am now if I were a well cared for corgi, or a five-year old child, or someone who has had a lobotomy. But that doesn't mean that becoming a corgi or reverting to childhood or having a lobotomy are acceptable outcomes. I wouldn't wanna be happy if it meant giving up freedom and equality and respect.
Feminism is about freedom and equality of opportunity for women as a class. Happiness, in turn, is up to the individual and there are no guarantees. To require feminism to serve up happiness on a platter for women is to ask of it something that is not asked of any other political or cultural movement or philosophy. And I think it's disingenuous.
This reminds me all too much of the controversy around the odious booklet written by local pastor Doug Wilson called Southern Slavery, As it Was. The booklet contends that the cruelty of American slavery was overblown, and that slaves in the American South were actually quite happy. The "evidence" used in the book is complete hogwash, but the premise is even worse. Happiness and human rights are different things - they are not mutually exclusive and unfortunately, having one does not mean having the other. I might be happier if I didn't get angry at misogny or despair at the moral compass of this administration, but more important than being happy is being a good person with equal moral standing to all other good people in the world.