This novel is written with the ironic removal ("limited omniscience," perhaps?) that the great male novelists of the early 21st century (Franzen, Wallace, etc) were often accused of. In that regard, Helen DeWitt can count herself as belonging to their ranks. In all others, she rates somewhere closer to Zadie Smith, whose White Teeth I found similarly insufferable.
"Insufferable" may be too strong a word. Dewitt has a prodigious imagination. Unfortunately, that prodigiousness does not belie focus. She writes with all the panache of a hyperactive cat lady, and her prose often descends into whimsy even in its depiction of brutality and immense sorrow.
There are moments of humor, but few of poetry. The soul of this novel remains hidden behind that ironic removal, behind the perspective of characters who seem too philosophically disengaged in the human project to be deeply invested in their own lives. Yet it still attempts to form some grand narrative of life, culture, and humanity circa 2000. Gen X continues to take revenge upon itself, deprived of truth by its rejection of all existing truths.

DeWitt is surely no cat lady (not that there's anything wrong with being a cat lady) and I don't get the Zadie Smith comparison either. Obviously this novel's never gonna please crowds, but as a fan of polyglottism and literary monomania (the second half with its demented digressions reminds me of Beckett's "Watt", which I also love) I'll always cheer for it. I actually picked it for a book club once and although there were of course haters, I was surprised how many people dug it.