Yeah, it's an irritant.
I try not to get any on my skin, but when I do, it typically doesn't irritate my skin, but then, I have pretty leathery skin, anyway. I make sure to wear my work jeans and gloves when I resin. And always with the 3M respirator. (Speaking of, my carts are now only fit for paintspray, now. I can smell resin inside the resp, now)
Now, what you REALLY don't want is getting it in your eye. That will BURN. See, what had happened was the can of resin I bought ($40 gallon can, yo) got rusted shut. Even the good ole channel locks weren't pullin' it. So, I took the truck's tire iron and smashed a hole in the top. (We leave the can by the door of my massive garage, and there's enough airflow that it doesn't cause any harm to us) Well, I poured some resin to mix, and I was putting the can down. Last 3 inches, it slipped from my hand, and some splashed out, RIGHT INTO MY LEFT EYE. I screamed, dropped everything, kicked over the can of acetone and smashed some stuff, while running for the sink in the bathroom on the far side of the house. Had my eye under flowing water for a good amount of time. It was bloodshot like crazy, and all fuzzy, and wouldn't shut right for the rest of the day. Ruined that big batch of resin I'd prepared, as well as the tub it was in.
So, wear eye protection, too.