This release includes several important improvements for site builder to be aware of: the main "admin" permission has been updated, and the menu items have been moved to the "media" config section.
The 2.x branch is a complete rewrite, adding new functionality and fixing some bugs. You can refer to the documentation page for the most important differences between 1.x and 2.x.
The full detail of changes between 1.x and 2.x can be found below.