Originally Posted by exaltedwombat
But DON'T GET COMPLICATED! If your book is going to be any use, it must work on a range of devices. For instance, the Nexus 7 is becoming very popular. A commonly-chosen eBook reader for it, Aldiko, seems to ignore quite a lot of stylesheet instructions. It's often best to simply pour in your text, surround it by <p> tags, and let the device decide how it displays.
I've been testing some of my epubs in Aldiko, and I have generally not seen a problem with my styling being ignored. I did have to enable an option to use publisher styling though, I think that was off by default if I remember right.
Aldiko, Bluefire, Mantano, Nook, Sony and Overdrive (no particular order) seemed to be the apps that did the best job of rendering my epubs as I have styled them.
Moon+, FBReader, Cool Reader, Fabrik and Kobo were not so good. The books are readable, just don't look as nice.
It's definitely a mixed bag of experiences!