I have found the compass attachment most useful when running around in unfamiliar area under tree canopy and covering too much ground to have my face in a GPS or map. The stories about them not being all that accurate have been around for a while-I can't agree with or dispute them-but without a sun or moon for dead reckoning it's easy to get lost even in places you have been before so any amount of direction finding capability is worth having.
When I first got my PVS7's, I rode mountain bikes a lot in a county park near where I lived. When I would get off work, I'd go ride the trails and I got disoriented a few times-sooner or later trails and trees start to look a lot alike and a few times I ended up exiting the park a few miles from where I thought I was and had to ride the street/sidewalk back to my car.
It's like anything else, you have to practice with your equipment to get the best of it, whether it be walking, riding, or driving. Having a compass is handy if you ask me.