I'm a bit in two minds about this one.
On the one hand, I admire its verve and ambition, and I do think that it pulls off the trick of demonstrating that, as Alex writes to Jonathan, "humorous is the only truthful way to tell a sad story". It made me laugh a lot at the beginning, and feel a lot at the end, and think a lot throughout. For the most part, it involved me and made me want to keep on reading, and I didn't find myself growing impatient with any of the three (mostly) separate narrative strands. Y'know, it's a Good Read, witty and clever and maybe even a little wise.
But on the other hand, I feel as if it tries to do too much, and in so doing falls short of what it could have been had its focus been a little less diffuse. It's as if Foer is trying to tick off all the big themes of literature and life (love, death, change, memory, family, communication, the individual in society) while also working to some kind of state-of-the-moment checklist of contemporary lit-fic tropes (writing on the body, metafiction/unreliable narrator, intertextuality, Borges, Invisible Cities, magic realism, interrogation of the possibilities of language/language as constitutive of the self, etc) and the result is that the novel sometimes feels overly precious and too clever for its own good.
For the most part, though, I think he does succeed in drawing it all together - he makes it work, so that the big old sprawling, covering-of-all-bases, tendency mostly works in his favour, causing me to quibble about rather than damn the book's inclinations in that direction. Yeah, Everything Is Illuminated is good alright, if not as good as it maybe wants to be - it has a heart and a head, and plenty enough of each and of real substance for me to forgive Foer's having slightly overreached himself.