Well, for one, it has integration with Firefox, as well as a separate "notifier", so you get a notice on your computer instead of having to keep checking your email. There's also Google Talk. And, with your emails, they save as conversations, so you can follow the flow of what was said. And, you can import your Gmail address book to Myspace or Facebook. There's more, I'm sure, but the best way to do it is to see for yourself.