Most of the time you hear people complaining about poison oak, and wondering what good can ever some of it. Around here it grows anywhere there's bright sun and it loves to climb oaks(its favorite) or a fir(in a pinch). It sends out little rootlets into the bark and moss(yes I've tugged on it to find out), but doesn't kill the tree.
What is good about poison oak? This time of year it is the first plant to turn to fire and lose its leaves(thankfully), finally turning a bright scarlet before the leaves fall.
It has a pretty palette of green to pink to scarlet, very pretty in the setting sun.
Poison oak makes lots of berries for the birds(a good thing), and keeps trespassing hunters out of our woods(another good thing). Most of all, I think its best good thing is that it makes me pay attention--so I don't wallow in it, of course, but watching for it as I wander in the bush sharpens my awareness for outlines and shapes, and I end up seeing a lot more.
It is very easy to uproot, and at least for me, when there's been a few good rains on the leafless stems, it's pretty harmless. I read once that the Indians would rinse off in a puddle or stream if they mashed around in the poison oak. I tried it, it worked(ok I didn't roll around in it, just brushed up against it. And I know I do get it if I don't wash it off right away, so I'm not one of those "immune" freaks). Your mileage may vary, of course.