Oh, yeah! It's nice, but generally takes a while.

I had a gf who really liked to do this (of course I enjoyed it too!). We'd be making out; after my shirt was open, my belt would come open and jeans would be unbuttoned. She'd reach into my underwear and oh, so gently begin stroking around the corona of my cockhead. It'd make quite a nice mound in my briefs, and eventually I'd cum and soak my underwear. The orgasm has a long buildup, and is very intense. I'd have to recover for a few minutes before I was able to strip and move on to fucking. My cockhead was SO sensitive after that first orgasm.