I like that it is so simple, you can create emails in seconds from your inbox or compose them directly with an easy drag-and drop interface! Also, they are constantly improving their product - we have just started using this tool but already noticed some great changes since last time when were used another solution (which was not as intuitive).
We use entrobots for all our communication internally within my team of engineers/developers at work; mostly because its super quick & easily accessible via any device anywhere around me :) It has helped us organize internal communications between members by creating introduction threads where people introduce themselves / share relevant info about projects etc., which makes everyone's life easier during meetings.