Airmail has a very clean and modern interface. On the left side of the screen are the folders (inbox, starred, draft, sent, snooze, trash) and on the right side the email threads for the folder currently being viewed.
Airmail can integrate with multiple Cloud services for syncing, creating backups, adding tasks and more. Some of these services include Dropbox, Box, Fantastical, 2DO, Todoist, Wunderlist etc.
Airmail is available for both iOS and Mac, for people who use Apple's mobile devices. And the interface between both platforms is quite consistent, making it easy to seamlessly jump between one and another.