There are some improvements to the book, but no story changes. A new table of contents and a cleaner EBook conversion have also been done.
Amazon does not push updates to their customers' devices automatically because that would result in the removal of notes and highlighted sections. They give you the choice instead - you can stick with the old version, or update to the new and lose your notes.
Here's what they said today in an email:
"We won’t notify customers of the updates, but they can now update the content on their “Manage Your Content and Devices” page (www.amazon.com/gp/digital/
So, if you'd like the update, please feel free!
The new updated version should be available on all other platforms within a week unless you got it at Smashwords, in which case it should be available in 2-4 hours from the time of this post.
Thank you very much for your patience on this!