Gmail is the application which has made me realize a big weakness of web applications. The web was supposed to make "application upgrades" painless and instant. After GMail's recent changes, I would really love to "download old version of Gmail"; however its web, I can't do that!
So was I, and I took it, and I'm still using the old version. Thankfully. The day they force me onto the new version I'll go back to Thunderbird, using the gmail backend only as a searchable archive.