I’ve been using it for a while and it is really very good. Much less buggy that our Exchange stuff. And it is great to see other people calendars. Works better than native Exchange really. Now, it does push mail too, so you don’t have to configure imap.
AppleInsider | Google brings push Gmail to iPhone, iPod touch
Google Sync, the service that allows users the ability to sync Gmail contacts and Google Calendar with the iPhone, has been updated to support Gmail as well, bringing push capability to the iPhone