I don’t mean to rag on iTunes, but, as music managers goes, it does kind of suck. I was intrigued by the new Genius sidebar in iTunes 8, though, so I gave the upgrade a spin.
The first snag is that the Genius sidebar has to examine every single file before it will start working. All 11,000+ of my music files are on network storage, which my PC accesses over 802.11g wifi. That took a little under 3 hours to complete. Yes, hours. Why did it have to rescan every file? Why didn’t it just use the database iTunes had already built (which, incidentally, took under 30 minutes including processing album art)?
So, after a half day of processing, I finally had a chance to test it out. As always, I started out with Metallica to see what comes up. Can anyone spot what’s wrong with this picture?

Yes, I clicked the link in the “Genius” sidebar, and, yes, it’s referencing the version of the song on Reload. Now, I understand it’s using heuristics to recommend alternative music. However, it’s doing a simple lookup for the “Songs You’re Missing”, so if the ID3 data matches (which it did), it shouldn’t show up on the list. Incidentally, it found 9 songs I “didn’t” have, 4 of which I did, in fact, have (everything except the new singles and the Swizz Beatz single):
Not to mention the albums/artists it just couldn’t “find”. The archaic stuff, I understand. However, I’m pretty sure this should have pulled back some results:

You have to get the simple stuff right.

