I have no doubt there are more scientific tests regarding the durability of PPF vs Paint, so this is simply based on my experience. Quality PPF is durable, but it will scratch/mar but I haven't seen it "tear" as it adheres to the body very well. The light mars/scratches kind of "self-heal" when in sun and others can be polished out by hand just like you would paint.
While I haven't had any deep scratches, I have had some dog claw marks from my 100 lb labrador jumping out of the hatch, but the scratches haven't reached the paint - thus the PPF is doing it's job.
For me, the PPF allows me to take it off road without the worry of permanent "desert pinstripes" or stone chips on the hood, fenders and bumper on the paint. If and when I go to sell, the PPF can be removed if too damaged or the buyer prefers the look of gloss paint.
Is it worth the investment? Only you can determine that. You could go without and do your own polish touch ups or re-spray if needed. It really depends on your use and needs.