I decided to give it a go. I copied my iTunes 8 app file, along with my .pls and zipped them up before install. Good thing too because iTunes 9 was on my computer all of 2 minutes.
Immediately I found myself not liking it. After the install Genius magically turned on. When I went to disable it I got a dialog box saying I needed to install safari in order to finish the request. Screw that. Safari sucks and there is no reason for it on my computer. I really did not even get to find other complaints, just right off the bat.
The iTunes LP is useless (To me) I currently have a bunch of "Booklets" that came with my purchases, and I have been thinking about deleting those as they just take up space. I have never once looked at one.
The whole library sharing is barely different from what we have been able to do for a long time. What would have been nice is the ability to share your home library while your out and about.
The interface is hard on the eyes. I did not go to the iTMS yet, but that looks like it is also going to be hard to look at.
I had a feeling I should stay with 8, I should not doubt myself.