I like that you can set up all of your email addresses here, so it is easy to switch between business accounts as needed without having to deal with forwarding emails or remembering different passwords for each account! This service does not yet support Microsoft Office 365 at this time - which would be nice if they want my continued use in 2019 (we are switching over from Salesforce).
If using Outlook365 instead of other clients such as Apple Mail, then there isn't anything too bad about their solution either way; but the benefit of being able to manage multiple domains/accounts through one platform makes them stand out above most others we have looked into thus far. We do enjoy using this software. It has been very effective since our team started working together within the same application rather than needing separate tools / applications to send messages among themselves via various methods.