The fourth novel in the Earthsea Cycle neatly bookends the tales of Ged and Tenar and the dragons. Two years after "Equal Rites" it sort of does the same kind of thing that Terry Pratchett did in opposing men's and women's magic but in Earthsea only the former is held to be of any importance. Why are men frightened of women? Well apart from the possibility of being killed, I think it's a matter of ostracism - the perception is that women make community, and men have to fit in even if they think they have power.
Some people have said not a lot happens in this novel but a lot does. Not a lot of conflict but when it is there it is effective. Whether Ged and Tenar should have got it together, well maybe not, but we don't live in an Earthsea society do we? If it's good for them why not? As Aunty Moss points out, women's magic never denied sexuality. Nor does it set itself apart from the earthiness of the rural world she depicts - but then to be honest I never felt the men's magic did either. Ged doesn't have much time for ivory towers, any more than his master did. He only uses magic when he has to. Arren doesn't even have any magical ability and Ged finds a way to train him nonetheless (soz, I just watched 'Kung Fu Panda' and I can but conceive of Arren as Po!).
It is darker than the other books, true, but it was written nearly two decades later and with more knowledge. Dark wisdom. But the dark needs the light - as the Taoist Le Guin would no doubt say - and the light needs the dark.