I'm not book designer, but a Kobo Touch and Glo user. I do edit my copies of ePubs to improve my reading experience, so I have some knowledge of the ePub structure.
Originally Posted by AlexBell
But a friend has tested it on her Kobo Touch, and it seems to be an absolute disaster - links don't go to the right page, the font size is too small, and there are several other problems. It's also a disaster using the Kobo app on my iPad2. The friend has tested other ebooks I've designed for me, and found although links didn't work the rest of the ebook worked well.
For the links, how much are they out? There is a navigation issue with the latest firmware (2.3.1 and 2.3.2). This is normally seen as reopening a book goes to a page or two earlier than where it was closed. I have seen some mention of links having problems, but I haven't seen them. The only books I have read lately with links were from a TOC to chapter headings. These worked perfectly. There is a workaround for the navigation problem. Setting the margins on the reader to zero sorts it out.
The only other issue with links I have seen is the actual act of selecting them. If the link is small, say a number for a footnote, and the font is small, selecting them can be next to impossible. Increasing the font size has always solved this for me. That isn't really practical and I don't know how other touch devices handle the same issue. I have seen discussion here or in the Sigil forum about how to handle the issue, so I assume it isn't just Kobo devices having the problem.
To me, font size should be set by the user. The Kobo devices have good control over font size. If an ePub uses relative sizes (em or whatever), this works very well. The same goes for the actual font. If the sized is fixed or the font is set, it can't be changed.