I've done it. Highly recommended just as a gut check. Most people are too chicken to get up there. But don't make it a career or anything.
I recommend "Comedy Bible" by Judy Carter to learn a few techniques. Most amateur comics suck balls and if you put in a little more time you'll be more appreciated. That said, your audience is gonna be a bunch of drunk retards most of the time so keep it simple. Also, keep it clean if you can, b/c you will stand out from the rest of the potty-mouthed losers...
One last note, I thought it might get me laid. Nope. Women believe all ths jokes you make about yourself. And there are not gonna be any attractive ones in any standup group or class you take.