The advantage is that third-party apps don't lock you out of your bird while you're out on location miles from Internet or cell service. If DJI locks me out ONE MORE TIME I'm jumping ship and either looking for a different platform altogether, or am going to look for a third-party app for real-time flight, not just automation.
That said, I have used Autopilot with good success. Beware that fully automated flight utilizes the iPad AS the Flight Controller. This is VERY resource heavy. So you will find on warm days that the iPad heats up and the app just shuts down mid-mission with no warning. If it's cool out, I can fly fully automated Autopilot missions all day with no problems on my iPad Air 1. If it's warm out (over 80°), I have to store my iPad Air Pro in the refrigerator over night, then keep it in a cooler on the way to the job site, and then fly my automated mission, keeping the iPad in the shade the whole time. If it gets too hot, the app just closes without warning, and the bird hovers in place.
It's amazing to me...with all this great UAV hardware that the software is so crappy.
Here's a video of my recent experience in the field. Thank GOD this didn't happen on a film set. You might want to turn the volume down on your sound card if the kids are around.