Mail for Gmail is a replica of Google's own web app, designed for desktop use and offering features such as an unread mail counter when sitting on the Mac OS Dock.

Well-supported by the developers

Mail for Gmail is essentially a clone of web Gmail, receiving constant (though not on-the-dot) updates from the developers as Google's web app changes. Basically everything is the same, and you can even get push notifications like those provided by other similar Gmail apps. It even works with Gsuites-exclusive Gmail features. The only real difference is how account switching works, where you have to sign out first.

Mail in your choice and get it back in a notification

Overall, Mail is a perfect solution for using one of Google's most popular apps on a compatible desktop. It suffers from its focus on Gmail only, providing no real ability to work with Google Drive and its ilk, but beyond that, it works excellently, making it perfect for both business users and home users, and only nearly perfect for those who are both, who might finde account switching a hurdle.