Originally Posted by artig
The second is illustrations. That may be specific to the titles that I've bought and read. But it is really annoying coming across the notes for a diagram or illustration at a random location within a chapter, and then not having the illustrations available at all.
The kobo displays illustrated epubs adequately (given the screen size). For examples, see Three Men in a Boat
or Perelman's Physics for Entertainment
Of course, they would be even better with hyperlinks so we could flip backwards and forwards.