For the iTunes (Apple) iBook, it is available to work on iPhone, iPad, iPod Touch and Mac computers running the iBook App.
The Kindle version is best viewed on Kindle readers and tablet sized screens running the Kindle App, like Android Tablets. The Kindle App does not allow zooming on fixed size books. So, while it can be downloaded to the Kindle App on a smart phone, it is always viewed at full page on the screen, so the data is too small to read easily.
At this time, the Handbook is not compatible with the Kindle for PC and Kindle for Mac applications. There is a "Kindle Cloud Reader" option where PC and Mac users can view the Handbook in their web browsers.
Kindle allows users to preview the Handbook and it is recommended to do this on your device running the Kindle App before purchasing.