As the theory goes, a proprietary ebook format is better because you know that it will just work.
With only one vendor controlling the Kindle format we are assured that certain features will work and thus enjoy a better "quality of the reading experience", right?
Wrong. While that may be true in theory, it breaks down in practice.
Take, for example, the Kindle fixed layout format.
This format is used for both digital comics and children's picture books. It was developed by Amazon's Kindle team and only works on the Kindle platform, but it doesn't work equally well on all Kindle devices.
Author and ebook maker R Scot Johns has been documenting how well the Kindle's fixed layout format is supported across the various Kindle apps, Kindle ereaders, and Fire tablets. He's been posting the results of his tests online in a chart, and earlier this week he updated that chart in response to the recent Kindle firmware.
The short version is that many of the features aren't supported consistently across the Kindle platform, and some aren't even supported consistently on a single device. Letterboxes, for example, behave in two different ways on the Kindle Android app. Depending on whether the ebook is a kid's book or a digital comic, the letterbox is either black or white.
If you're interested in arcane technical detail, you can find the chart here. It's a fascinating and frustrating read (the footnotes are longer than the chart itself).
The same goes for Johns' testing methodology. He's single-handedly built a suite of test ebooks similar to the ones used to track iBooks, Kobo, etc support of Epub3 for the EpubTest website.
These tests involve loading a minimum of nine different Kindle test files (more if some new variable needs testing) - each of which contain over a dozen pages that have been created specifically for this purpose - onto the seven different Kindle apps and devices I currently own. This creates a series of 72 iterations of a Kindle fixed layout file on a Kindle reading system, requiring a total of 1044 page loads (if each page is only viewed once on each system), and countless orientation changes of each device (which for the Paperwhite is a pain, to say the least), each page of which must be run through a battery of tests to determine what is working and what is not, pursuant to the ten items listed on the chart (only 8 of which I now test), and carefully noting any anomalies that occur. This tends to get somewhat confusing if one is not quite awake, and thus requires a lot of coffee (donations gratefully accepted).
You can find more details on his blog, The Adventure of an Independent Author.
When you get into the nitty gritty technical details, it turns out that the supposed benefits of a proprietary Kindle format are no more real than the opposing view that you can make one Epub file which will work on all Epub platforms.
Both claims are more marketing than engineering, and should be taken with a grain of salt.
image by tribehut