Modern & old-fashioned. An odd sort of magic mixed with a stark reality. A handful of contradictions, but not contradictory. 
 I've read one other book by Ruth Ozeki, All Over Creation. Both novels subtly incorporate numerous environmental themes that are worth exploring further in real life. This one - with the descriptions of Oliver's plant-as-art, the tsunami and ocean currents, the nuclear plant meltdown, a remote island in Canada that is being eaten alive by nature - is rich and lush and will probably make people squirm in their seats a bit. 
 Favorite Quotes 
 But in the time it takes to say now, now is already over. It's already then. Then is the opposite of now. So saying now obliterates its meaning, turning it into exactly what it isn't. 
 ...and even though I know you can't hold on to water, still I gripped her fingers a little more tightly to keep her from leaking away. 
 Life is full of stories. Or maybe life is only stories. 
 This agitation was familiar, a paradoxical feeling that built up inside her when she was spending too much time online, as though some force was at once goading her and holding her back...a feeling of simultaneous rushing and lagging behind. 
 Do not think that time simply flies away. Do not understand "flying" as the only function of time. If time simply flew away, a separation would exist between you and time. So if you understand time as only passing, then you do not understand the time being. To grasp this truly, every being that exists in the entire world is linked together as moments in time, and at the same time they exist as individual moments of time. Because all moments are time being, they are your time being. - Dogen Zenji 
 Both life and death manifest in every moment of existence. Our body appears and disappears moment by moment, without cease, and this ceaseless arising and passing away is what we experience as time and being. 
 Things that Occurred to Me Later 
 Haruki #1 is the crow! Duh! (There's a whole portion of his diaries/letters that talks about an old tale involving a crow and how much he loves to fly. Geesh, I feel dense.) 
 In the end, you never find out if Pesto (i.e Schrodinger) the cat survives, therefore he is both alive and dead to the reader, just like his namesake's theory. Duh #2. Really, it seems that everyone is both alive and dead. Nao, her father, Jiko... It all seemed so subtle, but now it's hitting me over the head! Duh #3. Alive and dead. Same thing. 
 Um, totally didn't make the connection that the character named Ruth is a proxy character for the author, also named Ruth. I am so dense. 
 Themes/Keywords 
 time and time travel, World War II in a Japanese setting, 9/11 in a Canadian setting, cyber-bullying, epistolary (almost), diary, crows & flying, suicide