I've wrestled with whether I should give this three stars or four, and as usual I end up wishing that Goodreads allowed for half stars. or something. Or even quarter stars.
For the most part, I quite liked it. I enjoyed Alex's voice, although I did feel sometimes like he sounded too much like an adult writing in a kid voice. Part of the problem was Alex's malapropisms, which are sometimes charming and often hilarious, but which also sound like an adult trying to sound like a precocious kid.
Alex himself is interesting, and Greene did a nice job bringing his readers a kid with a brain tumor and a seizure disorder (epilepsy, I guess) without being maudlin. There is not much in the way of OH WOE IS ME, and while there are moments of terrible sadness, it's not a tearjerker. I appreciated that.
His friends -- a girl named Chloe, mainly, and then a boy named David, whose relationship with Alex is confusing (but mostly in a good way) -- are good characters too. His parents... Not so much. Part of the issue is that Alex's view is so narrow, and so literal (much like the boy in Haddon's Curious Case), that the lens through which he sees his parents is also narrow and literal. Whatever the reason, they were much less defined and engaging than pretty much anyone else in the book, which is a problem (even the hamsters were more clearly written...maybe Alex thinks the hamsters are more interesting?).
Many other reviewers have mentioned that the book isn't linear, which, honestly, I didn't even notice (now that I'm thinking about it, I guess I can see where that might be happening).
STARTING HERE THERE ARE LIKELY TO BE SPOILERS SO BE WARNED
Despite everything, though, I really liked Ostrich, up until the very end. I wanted a MOMENT. Or I wanted the total lack of a moment.
One of Alex's preoccupations is the theory of Schrodinger's cat. He applies the theory to any number of issues in his life, and for the most part, that really worked. However, at the very very end, the reader is left not totally sure if Alex has died or if Alex has still not died. In some ways, that's appropriate to the book -- a lot of Alex's ponderings have to do with whether or not X is Y or Z, and with the ways in which the lid stays on the box (and the cat stays alive and dead). Leaving the reader totally unclear on whether or not Alex has died would make sense.
And to some extent, Greene has done that. Most of the last section of the book seems to be working toward that goal, designed to create the ambiguity. Having Alex stop narrating to be replaced by a series of letters to his mother from a prestigious secondary school Alex wants to attend, the headmaster of the school he's been attending, and the testing coordinators who decide his exam results...that actually sort of works. We don't know what's going on, and that's okay. It leaves the reader wondering whether or not Alex has made it/is going to make it/etc. The problem is Alex's mother's attempts at journaling, which feel intrusive and make the ambiguity feel forced.
So it just ends... with a whimper, not a bang, and with ambiguity that feels less like a cat in a box and more like confusion. And that's why I'm giving it three stars, instead of four.