GUI PART 1
The GUI Dune HD is using goes back roughly a decade now and since it's very easy to use i don't see any reason for them to change it (not to mention that their consumers have gotten used to it by now).
As usual from the sources icon you can access the internal flash memory and any attached media and network locations.
The latest news from Dune HD can be accessed from the news icon.
Inside the movies icon you can see details about various movies, including those on the attached media.
There are quite a few apps installed in the Pro Vision 4K Solo by default but you can install more (both Android and Dune HD ones).
AptoideTV can be used to install and use Android apps.