Well, if you are like me, there are things about iTunes 11 you don't like and prefer the way things were done in previous versions of iTunes, this is not to say I hate iTunes 11 completely, I haven't really explored iTunes 11, but it leaves out some things I liked and used like iTunes DJ. So until there is a must have feature... I decided to downgrade to iTunes 10.7.
Anyway, since I didn't feel like trying to remember (and/or figure out) how to this seamlessly, I googled "drowngrading iTunes 11 to 10.7"
The 1st solution that I saw and tried, worked.
Since I have noticed many others wanting to do the same, I have decided to share this info (it's really quite easy to do).
All I did was uninstall 11, install 10.7, and repaired a problem with the iTunes library (this is what I was too lazy to figure out)
The toughest thing to do is repairing iTunes library info (and this is pretty straightforward too), iTunes keeps backups of things, and what you need to do is find the library file "iTunes Library" (extension "itl") delete this (or rename it or move it, just in case) then locate the backups, and replace what you just deleted (renamed,moved) with one of the backups (try the most recent, if not, then the 2nd most recent, etc) I copied a backup and renamed that copy.
I have only tried this on my Windows 7 64 bit system, but the steps should be the same in other systems.
If you don't have 10.7, you should be able to find it here
http://support.apple.com/kb/DL1576 (32 bit)
http://support.apple.com/kb/DL1577 (64 bit)
or you can search apple for other versions
The iTunes library should be in the >> Desktop\Libraries\Music\My Music\iTunes (Vista, 7, 8) << folder.
>> My Documents\My Music\iTunes\ (XP) << folder
the backups should be in the >> Previous iTunes Libraries << sub-folder.
Also I guess if you use windows system restore, you could use system restore to roll back to a time when you hadn't installed iTunes 11.
Hope this helps you