Today I upgraded one of my desktop partition from Ubuntu 9.10 64bit to 10.04 64bit. The upgrade process is relatively smooth. Download from local Singapore mirror is quite fast. Installation is not that fast (more than 2 hours for 2700 packages, no KDE, just Gnome). But all in all the process is quite ok.
Just a minor glitch -- I was not using Network Manager but wicd. Prior to the upgrade, I uninstalled wicd and did not install Network Manager. Therefore, after reboot, I did not have the wired network. Still two commands away, I had the network up again (sudo ifconfig eth0 192.168.1.110; sudo route add default gw 192.168.1.1). Then I installed Network Manager and next reboot my wired network is automatically up.
BTW, the mirror seems to have problem with one qt4 package right now (libqt4-xmlpatterns). So I had to uninstall it before the upgrade.
The default theme has the window buttons in the left side. I still prefer them to be on the right side. So I change the theme back to Human.