I thought this comment by Egan said something interesting about his approach to fiction:

A few reviewers [of Incandescence] complained that they had trouble keeping straight the physical meanings of the Splinterites' [direction words]. This leaves me wondering if they've really never encountered a book before that benefits from being read with a pad of paper and a pen beside it, or whether they're just so hung up on the idea that only non-fiction should be accompanied by note-taking and diagram-scribbling that it never even occurred to them to do this. I realise that some people do much of their reading with one hand on a strap in a crowded bus or train carriage, but books simply don't come with a guarantee that they can be properly enjoyed under such conditions.

(I enjoyed Incandescence without taking notes. If, while I was reading it, I had been quizzed on the direction words, I would have done OK but not great.)

Edit: The other end of the above link contains spoilers for Incandescence. To understand the portion I quoted, it suffices to know that some characters in the story have their own set of six direction words (instead of "up", "down", "north", "south", "east", and "west").

Edit 2: I have a bit of trouble keeping track of characters in novels. When I read on my iPhone, I highlight characters' names as they're introduced, so I can easily refresh my memory when I forgot who someone is.