Games Workshop’s decision to publish it’s Warhammer 40K Codex books (and Warhammer Fantasy Army books) as eBooks is still a fairly new one, all things considered.
Thus far, GW’s eBook publications (as opposed to Black Library’s eBook publications) have been limited to publications for Apple devices, notably the iPad.
Now, Games Workshop expanded the range of devices you can read your Codex on. The Eldar Codex is now available for Android and Kindle. Curiously enough, these eBook-formats of the Codex are published through Black Library.
Perhaps, the odd recent “Codex-extract” publications by Black Library were, partly, a test for this.
If you give a non-Apple eBook-version of the Codex a try, let me know what you think of it!