I've put the upgrade log up on the URL above. I did an upgrade from RedHat 5.2 (running kernel 2.2.5). Mid-upgrade, my /usr partion filled up to 99%, and multiple packages errored out without putting anything to the screen. When I rebooted, I had to manually reupgrade the errored packages in the upgrade log from CD.
This has been fixed in later versions of the installer, and the installer now does disk space estimates.