DBXmum- have you ever read The Post-Birthday World? So much of it is beautifully-observed, and the narrator's voice is incredibly authentic-sounding, yet it is ruined by poor editing and over-research (did we really need to hear the lyrics of 'Snooker Loopy'?). It is so brilliant, like the rest of her writing, in getting into the head and emotions of her central character, but she seems to waste so much of this skill on narratives which are fundamentally insubstantial. WNTTAK felt important, even if you didn't like it- it had something to say about motherhood, PND, school massacres, etc etc...
I don't know (I haven't read Double Fault, for instance), but perhaps obesity actually is as deserving of commentary as youth alienation; perhaps the idea of how our fate unfolds (as in TPBW) depending on which partner we choose is also a subject worthy of serious contemplation. Writing this now, I certainly think "why not?". Yet somehow Shriver does not really succeed in batting Kevin out of the park.
It's interesting that your impression of her corresponds so neatly with how she comes across in interviews- cold and lacking in empathy- yet for me, her biggest strength as a writer is her ability to nail the internal monologue of her characters. I'm just not convinced that she quite manages to give us the 'Great Novel' she is probably capable of, and was foreshadowed with WNTTAK.
I do find her work very readable though, and look forward to her finding her groove.