Having this app installed will unlock every feature, allow color customization and prevent the displaying of a "Donate please" dialog in the free apps. Other than that, it also allows using a Shared Theme, which means that as soon as you change a color in one app, all other apps will be updated. Newly installed apps from the suite will automagically receive the shared colors too.
It comes with material design and dark theme by default, provides great user experience for easy usage. The lack of internet access gives you more privacy, security and stability than other apps.