Well, if you're not on Match, then the thing I read wouldn't apply to you anyway.

What it does, is put your music into the cloud so you can listen to it from any copy of iTunes that's online, rather than having to store your library on authorized devices. So anything that's for sale in the iTunes store (whether or not you bought it there) gets a tag that you own it; if you have music that they don't sell, it uploads a copy (which I'm told can take for-freakin'-ever if you have a lot of music).

I'm not bothering with it, myself.