I've been messing around with the fonts and sizes ever since I received my K3 and I finally settled on condensed. The regular caecilia font looked too "happy" to me. I'm not sure if that bothers anyone else, but it seemed weird reading books with a serious or sad tone that were using a font akin to comic sans (ok, I know it's not that bad, but you get the point). But after spending some time with the Kindle I don't really notice the font as much as I did in the beginning. It would be nice to have a font hack, though.
Edit: Maybe I wasn't too far-off comparing caecilia to comic sans.
