For instance, if a book has an embedded jpeg, you can tap it and enlarge it to fill the screen. But if it is SVG art (as we often use for line art like charts and maps), it will not scale. Why not? I don't know. There is no support for MathML, or for scripting of any kind. Support for embedded video is poor. Page lists are suppressed in favor of Amazon's own proprietary system. Note that epub readers like Calibre and Apple iBooks can manage these things. It is intrusive about formatting: it may decide that your lists need to be bulleted whether you want them or not. It always underlines links, which is a pain with note callouts. These behaviors may be inconsistent across devices.
Adobe Digital Editions supposedly supports most of the epub standard, but is a buggy mess, esp. the Windows version.
> These behaviors may be inconsistent across devices.
The image handling inconsistencies are very annoying. Here is what I've seen with several books.
1. When read on an eInk Kindle, images are small. (I can tap them to bring up the option to zoom, and zooming does work, but it is kind of ugly). For example, I've seen chess books where the diagrams are about twice postage stamp size, whereas in the physical book they are about 3 or 4 times as big in each dimension.
2. When read on the Kindle desktop application on Mac, the images are bigger. As far as I can tell when I've been able to compare to the physical book, they are the correct size.
3. When read on the Kindle desktop application for Windows, the images are small like they are on Kindle eInk readers.
4. When read in the Kindle cloud reader, they are the right size like on the Mac desktop application.
5. When read on iPhone with the iOS Kindle app, the images are small.
The main places I've noticed these are with chess books, where the position diagrams are the victims, and math books, where diagrams are the victims, and often also equations if the equations are done as images.
Image sizing is a tricky issue. When ebooks started to become a more mainstream thing, image size in the file was limited by the vendors, and also we sometimes had third-party licensing restrictions. Over time, of course, devices got more memory and higher-resolution screen, so larger file sizes are allowed, or even desirable. However, consistent behavior is still elusive. And that's even assuming optimal coding on the part of the publisher or whoever is doing their conversions; they may be using files that are not adequate for the higer-res screens.
Adobe Digital Editions supposedly supports most of the epub standard, but is a buggy mess, esp. the Windows version.