Same as every half year, I had problems with upgrading Ubuntu. Here are some of my problems, for some of them I have already a solution. I will add any problem or solution I hear from.
You might also want to have a look at the Ubuntu 7.10 Release Notes

The tty1-7 consoles do only display garbage.
This time it was not fixed by changing the kernel vga parameter to a suitable value.
Update: Solution found - No tty1-6 in Ubuntu 7.10 Thanks, André.

There is a bug in the xserver-xorg-video-intel driver, see this Devlog entry.

When I change the Dual Head configuration, my xserver does not want to start again. I have an ATI card, I told you already.
I am currently trying these: intellinuxgraphics.org wiki.debian.org …without any success.

Tilda crashes when you open it. A bug entry and a workaround exists but no update yet. Launchpad Bug 144175
Workaround: ”Enable animated pulldown from Right or Left, set delay to 1 usec [I would recommend 100 - works better]. The result is about the same as without pulldown animation and it works correctly.”

I cannot reach the printer job window anymore from the printer configuration tool (like it was in Ubuntu 7.04). Where is it gone?
I apt-getted the gnome-cups-manager and now I have it back again. Quite funny: Now I have two different printer config tools, both are in my System→Administration Menu.