Is this good?

This is a genuine question. I am not sure whether this is good or not.

It seems to only extend existing options? Or is there some trade-off?

This is awesome!

For one to have an open-source client to Exchange online and on-premise with broad support for more than plain email management. And also for other servers like Kerio Connect and grommunio.

Current limitations:

  Search & filtering
  Filter actions requiring full body content are not yet supported.
  
  Accounts hosted on Microsoft 365
  Domains requiring custom OAuth2 application and tenant IDs will be supported in the future.
  
  Accounts hosted on-premise
  Password-based NTLM authentication and OAuth2 for on-premise servers are on the roadmap.
  
  Calendar support
  Not yet implemented – calendar syncing is on the roadmap.
  
  Address book / contacts support
  Not yet implemented – address book support is on the roadmap.
  
  Microsoft Graph support
  Not yet implemented – Microsoft Graph integration will be added in the future.