Content warning Kind of hard to discuss the 'but' without giving something of the plot of the book away
It's not that the story wasn't good to read, but there's something not so enjoyable about the it. I'd guess it's because it feels like reading a critique of a biological deterministic view of power, or one that only sees power relations through the lens of patriarchy/matriarchy. This leads to a story where the abuse of power by men swaps for exactly the same behaviour in the same structures by women.
Maybe it's the nature of power, but it feels more a perspective of it that only sees it one way which after a while makes it a hard read.
Even under the pretext of the book - women becoming physically stronger than men through having The Power. Would no other structures really change? Would society be so exactly reproduced?
But I guess that was the point of the book.