Meg has already written a treatise on the subject, but I was asked to weigh in as well. So here it goes.
Pro: Free time is often spent quietly on the couch together, working on our respective projects, listening to music, and enjoying each other's company though not saying a word. Quite meditative and fun.
Con: Unfortunately this is a little too easy to do, so we don't end up spending much time doing other things together... like housework.
Pro: I usually end up doing most of the weekend driving in the relationship. This works well, as I seem to enjoy it more than Meg. It is nice, however, on longer trips to be able to break up the driving a bit and give myself a bit of extra time to knit.
Con: When I am in the passenger seat knitting, I'm usually thinking about how I am taking away from Meg's knitting time. Crazy, I know, and not really fair to myself. But there you go.
Pro: Grandmother is ecstatic that we both knit, and Mom thinks it's pretty neat.
Con: Somehow it really pisses my brother off.