Update: Caution, iTunes 10 Extremely Buggy
Yesterday I troubleshooted iTunes v10.0.1 for my client. The issues my client was having was iTunes 10 would not literally play anything in the music library regardless of the file format. Another thing I ran into was that iTunes 10 interferes with the System sound. The System sound will not come back on until you quit iTunes 10.
There is a possible fix for certain issues in iTunes 10 involving re-installing iTunes 10 with this installation procedure at http://reviews.cnet.com/8301-13727_7-20017359-263.html.
Right now I'm concerned about how well iTunes 10 will work with the new Apple TV. As soon as I get my hands on a new Apple TV, I will do thorough testing and shake-down of the new Apple TV and iTunes 10 streaming system along with testing everything else in iTunes 10.
I will bring my testing results here at the Blog and on my JohnAtMacMobile twitter also. Stay Tuned.