First application is going to be hell, I'll tell you that much. After that it gets much easier. I mean, with the initial install, every tooth has moved slightly, and just that slight move is going to be pretty nasty for the first week or so. Once they've moved to the place they're supposed to go, it's a lot easier. After a month, you'll hardly notice them untill you go in for another adjustment. Though, with time, like most things, it gets more and more bearable.
Here's one thing too that's important. Bands, on your molars, will trap all sorts of nasty stuff. Be sure to brush every day, if your orthodontist is smart, he'll give you a flouride gel to brush with after normal brushing. Rinse often. Dont chew sugared gum or anything with lots of sugar in it cause it'll get inbetween the band and the tooth. When I got my bands off, I had a little decalcification on my molars, which eventually led to having them drilled and filled later on.
*obligitory horror story*
I had to have braces because I was missing a few permanent teeth. A molar, and my two front lower teeth. (goofy lookin eh?) After 6 months, a wire slipped out of the bracket right after I got an adjustment. I went my 30 days till my next scheduled adjustment with the wire out cause they're damn hard to put back in yourself. When I got back in, all the teeth had moved cept for the one that wasnt reinforced by the wire. The orthodontist took the pliers and started *wrenching* the damn tooth/bracket back onto the wire. People outside said he looked like he was working on a car or something with a ratchet. my GOD that was painful, but after he got the bracket reattached to the wire, everything was okay.
So, be nice to your teeth with braces..