Like the poster above me had a large flare up at the start which was gotten rid of by a fairly intensive course of steroids.
Roaccutane did greatly help but I suffered worse side effects than most I think. Very dry skin and lips, inside of nose was also dry causing regular nose bleeds. More importantly though I did get some of the depression side effects of it, though I must stress it is quite unlikely you would get that. It's just something to consider.
Was on it for about 6-9 months, took a break then went back on for another 6 months. Skin is now fairly clear though I'm still on minocyclin (a fairly mild antibiotic) and using isotrexin cream to keep it under control. Also, be warned that although it may clear active outbursts it does not clear scarring, my skin is still fairly heavily scarred over a year on.
But my experience is, from what I can tell, a fairly unusally negative one. I just feel the need to give it because usually all the posts on a thread like this tout it as some sort of wonder drug, and I don't want you (like I was) to be given too much false hope. I'm sure it will work brilliantly, but prepare yourself for the eventuality that it doesn't.