We are working on the transition from Outlook Classic to New Outlook, was curious about what other organizations are doing specifically around whether or not you are forcing users to switch to New Outlook and retiring Classic Outlook or are you allowing users to select which client to work out of until Classic Outlook is retired? Also curious what resources your org used to help with the transition or introduction of the New client.

Its a transition but new app has some limitations.

Adoption is very slow, many are switching back.

Our users really aren't fans of the new Outlook. I'm in agreement with Omar, I don't see a need to force the change at this time. Those that have switched, eventually switch back stating it's frustrating to use/navigate. I'm sure MS will force the change for all of us at some point though. 

Until now, I did not see the need for the new outlook. Also the new outlook has limited features compared to classic. overall reduced customization and compatibility issues with older system's protocols which may cause a disruption, But on the other hand you also have security features that could be the reason to use the New outlook.