I've been using GMail as my primary e-mail for the past month, and it's worked pretty well. Searching e-mail is nice, the tagging features are helpful (for instance, I added a tag for a client which automatically includes every e-mail which contains contains their domain name), and it integrates well with the Google personalized desktop.
"oops...the system was unable to perform your operation"
I checked with friends via chat, and they were able to get their GMail just fine - it was just my account. I tried other browsers, cleared cookies, even tried other computers; same message. Searches revealed others who'd had the same problem, but no solutions which worked for me.
This was a problem, since my e-mail contained conference call numbers, important project information, etc.
GMail does provide a POP interface, so I'll probably run an e-mail client to keep a local e-mail copy in case this happens again. I'm posting this in case someone has come up with a solution to this problem and to recommend an offline e-mail backup (which is just good sense, anyways, in case the internet connection goes down).