hmmmmm..........if I were you, I would re-think that. OSB is very rough and coarse-textured. If your reasoning is to 'avoid taping', then why not just go ahead with drywall and not tape it? At least then you'd still have a nice smooth surface (just not the un-finished joints and fasters), which you'll never get with OSB!! Then, down the road if you or someone else wants it smooth, it would at least be possible to really finish it off with proper drywall taping and re-paint it.
Another more durable alternative would be MDO (medium density overlay) plywood, which we use in the sign business to make sign faces. Basically, plywood with an impregnated paper face which will be smooth as glass, if you want it to be! Of course, this doesn't have the tapered edges that drywall has, so taping it at some point in the future would not be a good option if you went this route.
OSB is just a rough, nasty, dirt and dust-trapping, splinter-filled mess that I'd avoid as a 'finished' wall surface at all costs, but everyone likes something different! It's basically rough, large splinters pressed and glued into a wafer-----something you'll remember every time you brush against it! :S Do it once------do it right. It won't be much more work.
