So I looked into it somewhat… and quickly realized that for those of us writing novels, short stories, anthologies – basically text-based works – that the drawbacks and learning curve aren’t worth it.
The whole point of using a real eBook format instead of PDF is so that the text can fit the screen – because you don’t know what font size or even what kind of device the person is going to be reading on. They could be reading it on a PC, on a phone (of different resolutions), an eInk reader, or tablet. And I want that reading experience to be roughly the same across platforms. Or to put it another way:
The presentation of the text may enhance the work, but must never distract from the work
I’ve pointed this out a few different times – the example showing how drop caps can completely bork your work is a good one – and that philosophy underpins why I’m not using ePub version 3. I don’t know what my readers are using, and I want to ensure that it renders the same across devices.
Here’s one of the example ePub 3 files (the Wasteland, to be specific – and not obfuscated fonts, because I know that problem already) rendered across several different devices. There is neither consistent support for the Greek lettering (which I would have solved by using an image) or for the linebreaks.