My own bug experiences
Wanted to chime in with bugs I've found, though I am generally happy with lion. I especially like full screen mode because it fits into my workflow really well. In my opinion, some things should always be full screen --- Mail, Calendar, iTunes, and Terminal (so that I don't get distracted when writing in emacs).
Anyway, bugs:
1)In Mission Control, you can't drag and drop a window from the spaces running on a second monitor to a space on the primary monitor. This is weird, since there no such restriction when not in Mission Control.
2)Sometimes Lion forgets my wallpaper setting for the spaces on my second monitor and instead simply shows a dull grey wallpaper. It gets stuck in this state, so I can't reselect the wallpaper I want to use w/o shutting the laptop lid and re-opening it or logging out and logging back in.
3)This one is a bit scary. Sometimes all of my apps stop accepting input from the keyboard (both the laptop one and my external Kinesis keyboard). However, system commands, such as CTRL right arrow to change spaces still work. Simply shutting the laptop lid and re-opening it seems to resolve whatever is causing this problem. It's possible that the problem is caused by a weird interaction between my specific external keyboard and the laptop.
4)Aperture 3 does not work well with Lion --- there's got to be a memory leak. Simply leaving it running degrades system performance to the point where everything becomes choppy.
5)I'm having trouble using Kerberos 5 authentication to connect to my IMAP mail server. Sometimes it seems to work, sometimes it doesn't...
Is there some website we can report bugs to Apple? Safari has a "report bug..." option, but I don't see anything for the OS... [Edit: Never mind...Found Apple bug reporter]