I respectfully disagree. Nothing wrong with a simple design that deviates from the "standard" behavior. Most UI metaphors including the standards require some learning. Even the desktop icons need explanation to the users initially. Most users are ok with training if the UI is simple enough to pick up.

For example, this app has non-standard UI but has very simple UI that the users can pick up quickly. https://play.google.com/store/apps/details?id=com.mhillsyste...

Clear and Rise are perfect examples of simple UI that can be explained and picked up quickly.