As in the iTunes feature. If you use it, you probably know the drill. Pick a song, click the button, and maybe you'll get a pretty decent playlist. That's just it though, maybe you'll get a pretty decent playlist. Sometimes it'll actually be a few songs that really do go well with whatever song you start with, but there's often a lot of stuff that doesn't. For example, I made one for Bittersweet Symphony a few minutes ago. I've reduced the list to five (counting Bittersweet Symphony) after getting rid of Van Morrison, Devo, Steriogram's Walkie Talkie Man, etc. And a lot of the content that I took out was pretty good stuff, too. For example, I like Walkie Talkie Man. But when I'm listening to Bittersweet Symphony and I want to hear more songs like it, I don't want Walkie Talkie Man.
What I'm getting at here is that Genius is too broad. It seems like it's trying to base suggestions off of a perspective that covers too many different tastes. For example, I have most of Franz Ferdinand's works in my library, and I also have U Can't Touch This. So does that mean that if you make a playlist based off of U Can't Touch This, you should get The Dark Of The Matinée? Nope. There should be a way for you to modify the playlists after they're made as a way of "showing" Genius what you think should go with that song. If I'd built the playlist for B. Symphony, it would've included songs like Exodus Honey by Honeycut, Bytecry by Weevil, Aluminum by Barenaked Ladies, etc. It ended up being that none of those songs were in the playlist, which is unfortunate since I think they all go well with Bittersweet Symphony.
Anyway, in case you're wondering, the playlist I have after reducing it so much is Bittersweet Symphony by The Verve, The Dark Of The Matinée by Franz Ferdinand, Dashboard by Modest Mouse, The Safety Dance by Men Without Hats, and How Bizarre (Mix) by OMC.