It works under Adobe Air, so we don't have to care about the OS we are using because it runs on any Operating System.
Its interface, although similar to Gmail, includes some details that make it more solid. It's something between online inbox and email clients.
You can access all GMail sections: inbox, sent, bin, favorites,...
Of course you can write and send e-mails or answer those you have received.
Enjoy all the power of GMail and something else thankks to Geemail.