The new music recommendation feature in the updated iTunes promises will make playlists of songs in your library that "go great together"—or at least, that's what Steve Jobs promised during Tuesday's Apple event. But does Genius have perfect pitch, or a tin ear?

Here's how Genius works: One you've upgraded and launched iTunes (which will automatically start processing your album art for the new "grid" browsing view—get ready to wait), you'll see a new sidebar on the right. That's the Genius sidebar, and you'll get the option of turning it on or leaving it off and hiding it.

If you decide to turn Genius on, iTunes will start scanning your entire music library—a process that could take some time, depending on how many tunes you've got (my 3,400-song library took about 40 minutes, albeit on my aging PowerBook G4). After that, iTunes sends all the info it's gathered up into the "cloud," where it'll mingle with the song information from other Genius users. (Jobs says your song info will be anonymous; still, if you're paranoid, you should probably just turn Genius off.)

Once your tunes are all processed, you're ready to start Geniusing. Click a song in your iTunes library, and the Genius sidebar refreshes itself with recommendations from the iTunes music store—most of which were pretty obvious, such as other albums and tracks by the song's artist. If Genius doesn't recognize the song (which happened a lot, especially for my classical and electronic music), it'll just list the most popular songs (in the same genre, if possible) on the iTunes store.

Not too exciting so far, but the big draw of Genius is its automatic playlists, built just for you. All you have to do is select a song and click the Genius button in the bottom-right corner or iTunes; instantly, a playlist of anywhere from 25 to 100 pops up based on the song you picked. (You'll also be able to create Genius playlists—on the fly—on the new iPod Nano and Touch.)

So, how well does it work? Well … hit and miss, at least for me. A Genius playlist based on "Bad to the Bone" got me "Renegade," "Whip It," "Long Cool Woman," and "Panama"—not bad. But I also got "Old Man" by Neil Young (maybe just a shift change), "Nothing Compares 2 U" (hmmm), and "Don't Go Breaking My Heart" (double hmmmmm).

I tried some other playlists, and in general, I got about 80 percent hits, 20 percent misses—fair, but not a lot better than the other music recommendation engines I've tried (and never used again).

Of course, Genius' picks and recommendations are supposed to get better as time goes on, and as more users send their library info to the iTunes "cloud." Given that, I should probably give Genius the benefit of the doubt, especially on day one.

Still, I wish there was a way to tell Genius that you liked a particular pick or hated it, or to filter the choices in some way (as you can do with iTunes' Smart Playlists).

I also noticed that for now, at least, Genius failed to recognize many of the songs in my library—especially those that aren't for sale on iTunes. That might not be a problem for those with mainstream tastes, but if you've got a lot of avant-garde or otherwise obscure tracks in your iTunes library, Genius might come up empty more often than not.

Want to give Genius a try? It's available now as part of the free iTunes 8 upgrade, and you can grab it right here.

So, Genius impressions, anyone? Let us know.