To answer a few questions - The toolbar is different and will be bottom aligned on community devices like surface hub and MTRs to make it accessible.
Why you shouldn’t install an app outside of stores?
1. You never know what this package has, it could have virus and trojan 2. The old version of the app will no longer be maintained by microsoft 3. The move to the new app will enable us to build on top of the existing microsoft tech stack, the update is just the first step to this process. The chronology of events are Windows app update (which will then give unified experience across platforms) -> One drive migration (more secure and collaborative features like external sharing, search and similar experience to word file/excel can be built -> collab cursors, attribution, external sharing, sharing through email id as well as link based share and a lot more features will be built on top of the existing one drive tech stack.