Zoë herself is rather delightful, with a line in sarcasm that readers of her creator's blog will recognise. The other characters seem fairly three-dimensional as well. The political background, and behaviour of the most senior political leaders, once again doesn't make a lot of sense (a standard complaint of mine, and of course a YA novel like this more or less has to involve the protagonist getting one up on the adults) but it's a decent enough story apart from that.
So, my Hugo voting order: a close run thing, but definitely Anathem first, followed closely by The Graveyard Book. After that it gets even more difficult to choose between Saturn's Children, Little Brother and Zoë's Tale - the Stross is probably better than the other two but unfortunately has anthropomorphic robots which I object to. Thanks in no small part to Scalzi's efforts, you can join the Worldcon and download four of the five books for yourself.