I'm going to leave aside the arguments about whether the changes are good or bad. Personally I think they suck, especially moving the tabs to the left side of the page and the mail preview that can no longer be turned off. But opinions of suckiness aside, the point is that I was/am familiar with how my iGoogle page works. I don't want to have to adapt to some new way of working because some Google engineer thinks it's "better" for me.Maybe eventually I will, but at my own speed and inclination, Google, not yours.
Hidden on the "Google Operating System" blog are these instructions to get the old interface back - at least temporarily:
If you have the new version, but you prefer the previous interface, go to the settings page and select English (UK) from the list of languages. Please note that this is just a temporary fix.