In addition to what steveklabnik said, it's also nice that you can integrate all of the Google App services into your system and quickly and conveniently work online and share things via Docs and Calendar by company domain. It makes it super convenient. While there are some certains on privacy, I don't feel the threat outweighs the benefit. It's not like Google is sniffing around to know what you do via your personal email and stuff. They are using that data to target ads. And to be honest, that doesn't matter to me as much.