Half way finished after 20 minutes.
Update: Finished downloading 10 minutes later.
Installation: Took about 45 minutes on an old iMac Core2Duo 2Mhz machine. Nothing to the upgrade, about as easy an OS upgrade as I've ever seen.
Likes: The Mac feels snappier. All my applications work. The new Launchpad is cool.
Dislikes: Mouse scrolling was reversed. Immediately reversed it back to standard. Why would Apple change this?