I guess the featured improvements below will be more effective on newer devices. That means conservative users like me who fear incompatibilities with newest 64 bit octacore processors, Android Marshmallow or even Lollipop will probably see little difference on their slightly outdated configurations.
(1) Replaced "swipe-up" with explicit on-screen button for options menu.
(2) Improved graphics for all on-screen buttons.
(3) Minor layout improvements for some dialogs.
The network version which allows playing with remote PC engines is not yet made available by Aart. So, if you are using this feature, stay on 5.1.5 for now.
Here's the link to the new version without network permission, available for download at: GOOGLE PLAY