When we were kids we always nibbled on salal berries, so I have a soft spot for them, but honestly, they're not really very tasty.
I know you can make tea out of the leaves (but I'm not sure what medicinal properties). I think the most common use is to make a jelly or sauce, with lots of sugar, and the seeds strained out. I don't think I'd go out searching for salal to try it, unless we were studying regional foods or something, but if I had a yard full, I'd be right there, at least once!
The sauce is supposed to be good with game and salmon, and the jelly recipes I've seen are usually mixed with currant or oregon grape or some other berry (but not always).