My upgrade from Intrepid to Jaunty went smoothly. I run off of a Dell Studio 15 with an external monitor at work. Unfortunately, this creates a virtual screen size greater than 2048×2048 which is an issue with the intel graphics driver, not compiz, so I unfortunately cannot enjoy the bling. However, when I am remote, compiz works great. Metacity is great, but after being spoiled by the eye candy it is hard to go back. This is coming from a guy whose favorite window manager was Enlightenment
The popups on Jaunty have received a major facelift and are more pleasant. The login screen has changed, as well as the bootup splash screen. In my normal use, I have not stumbled upon any issues. If you have a similar setup, feel free to take the automatic upgrade path.
EDIT: Two things that have annoyed me, that might annoy you:
I prefer to restart the X server through keystroke: Re-Enable Ctrl + Alt + Backspace
sudo apt-get install dontzap sudo dontzap --enable
Enable blacklisted X3100 (GMA965) graphics for compiz:
echo "SKIP_CHECKS=yes" >> ~/.config/compiz/compiz-manager
There is a bug in the intel driver that has caused it to become blacklisted. Enable at your own risk, but since we have been running this driver for a while, it is probably safe.