I thought the book was okay, but that was all.
My main criticism is that it was massively overwritten with far too much over-analysis of the different characters, their backgrounds, motivations and appearances. So much so, that they felt over-constructed and simply didn't ring true for me. And no, they weren't tremendously likeable.
I felt the analysis of motherhood had its moments - and the parts that felt more authentic to me tended to feature the characters' offspring. I, too felt uncomfortable about Martha's lack of focus on her son, but actually I think that was quite deliberate on the part of the author (and the narrative later balances it out with the other mother/son dynamic).
The main problem was that the book didn't know what it wanted to be - a serious literary examination of adult relationships? A basic love story? For me, it fell somewhere between the two and wasn't really satisfactory either way.
Although I believe this isn't the author's first novel, it felt like it. A bit half-baked and trying too hard. Some witty lines here and there, but just too overblown.