Just upgraded to Ubuntu 10.10, but not without a few glitches.
1. I did the usual alternate cd upgrade
2. Upgrade froze with about 20% left. Restarted computer but could not boot into X.
3. Decided to use recovery option in grub boot menu
4. Manually mount the alternate cd iso, and ran sudo ./cdromupgrade from terminal. This miraculously solved all problems. It appears to "resume" the upgrade process.
Conclusion: running ./cdromupgrade from cmd line seems like a good idea for future upgrades. Its definitely faster too. It might also be a good idea to defer the Internet update until the upgrade is finished.