The Genius Feature is totally unpredictable when you get started. It won't get to know your tastes until you let it run for a few weeks. This can be more likened to Artificial Intelligence than a proprietary algorithmic solution that Apple developed. Or a nice combination of both.
But, the more you teach it, and let it work for you, the better it'll get. (like any good employee)
I have not seen Apple explain the mechanics of Genius anywhere yet, but I gathered that Genius does not actually make recommendations based on
your tastes. Rather it swirls your tastes in with other iTunes users' tastes and pushes out the collective wisdom to everyone.
I am still not 100 percent sure what Genius is actually doing:
1. What is it uploading from individual users? Steve Jobs said in the keynote that it will take into account my ratings and play frequency, but is it analyzing individual playlists, how closely together in time I bought certain songs, songs I bought but did not play very frequently, etc.?
2. What does the Genius mother ship actually do -- assign something like a Myers-Briggs value to each track and then "teach" my iTunes the values of each track in my music library? Or does it a huge multi-variant database that compares every track to every other track, assigns a proximity value from each track to each other track, and then push down to individual users only the info it needs? (If the latter were the case, Genius would not work on a new song unless either you update Genius after the download or the download comes with a Genius update.) Also, the Genius lists that I have run are careful not to overload the same artists so it definitely considers other factors than assigned values.
In the couple of hours I tooled around with Genius last night, I was very impressed with the lists it produced and with how many songs it picked that were perfect for the list but that I had not heard in a while.
Also, iTunes 8 on Mac is a
serious memory hog. With also-hoggy Firefox and a couple of other apps running, my 1.5 GB of memory was huffing and puffing at times.