I am bumping up it’s rating due to the amazing descriptions of synesthesia (see: http://en.wikipedia.org/wiki/Synesthesia) I’ve read in a book – it’s about the first time this condition has been touched on, at least that I am aware of, and the author does a masterful job of making you aware, bit by bit, of what she smells, tastes, and sees, and eventually unfolds what it is, since the protagonist isn’t aware that what she has is a medical condition – that she’s not crazy, since her family treated it as such, not knowing themselves. I would have been happier if the book had stuck with that, rather than adding a SF level to it, which I thought was superfluous, but all in all it was a good read, and well worth the descriptions alone. And she threw in tetrachromacy – a condition , usually in females, where they have four cones instead of the usual three, allowing them to see into spectrums normal humans can’t. See: http://en.wikipedia.org/wiki/Tetrachromacy
In doing some quick background research on this, I discovered that I may be a number form synesthete, since I see all time as a line, and the months and seasons as a circle. Fall is on the far side of the circle, around the “corner” from summer. “Number form synesthesia, numbers, months of the year, and/or days of the week elicit precise locations in space (for example, 1980 may be “farther away” than 1990), or may have a (three-dimensional) view of a year as a map (clockwise or counterclockwise).” Interesting.