Google first revolutionized search technology. They blew away Yahoo! (although I still use it) and even had the privilege of leasing out their technology to Yahoo! Search, at one point in time. Google’s introduction of email has now revolutionized the concept of email. With many pros and a few cons. Apart from forcing free email providers like Hotmail and Yahoo! Mail to increase their storage (to 250 MB and 1 GB, respectively), their email system has forced migration from many paid email services.
The pro’s of Google have been talked about everywhere. They are still on the invitation system (is it true?) but it is now really easy to get an account. There is a huge surplus of invitations going around now, and Gmail is virtually free to register for, now. For me, the biggest positive about Gmail is that it’s quick, it has huge storage, and it groups conversations. This can be used to follow the history of a ’conversation’. Secondly, one does not have to worry about storing Sent Items and wasting space. POP3 service is also a positive, but the viewing is messed up when downloaded through an email client.
The only negative I can think of in Gmail is that they have replaced Folders with labels. I much preferred the folder organizational system and find the label system too scattering. That apart, I am happily looking forward to Google Messenger (hoping that it will come out.) =)