Hi. I've only walked one Camino (littoral route out of Porto, and then joined the coastal at Villa do Conde...got as far as Vigo), so don't have a frame of reference by which I could compare it to other routes.
I absolutely loved the walk, and can't wait to resume it.
I never felt truly isolated, though I did have long stretches without seeing anyone.
And I did have one uncomfortable experience,. I believe it was as I was leaving Costelho and starting to walk up a quiet street near the bus station. A guy appeared asking me for money. He was pretty rough-looking, and unfortunately, I didn't have anything in my pockets, and didn't feel safe opening my backpack with my wallet around him. I told him I didn't have any money, and he challenged me on the point (how could I be walking the camino without money, he quite reasonably said), and began following me, being verbally persistent. Not feeling comfortable proceeding further, I turned back for the road and ultimately found a taxi to drive me a couple of kilometres ahead (I initially felt great resentment at being denied "my" camino experience, but the kindness of the people who helped me find that taxi made it an even better experience).
Nothing about this experience has discouraged me from getting back on the Camino, and this is certainly not being written to dissuade you. Just a way of saying that these kinds of things can happen, and might be somewhat likelier on the less busy routes.
Take care,
LorneB