It handles better IMO, quite better nd easier camera controls. And don't forget portability. The Mavic seems to be more sensitive to winds than the phantom. But that could just be me
From my experience between the P3S and The MP:
Pros of MP: Faster, easier to transport, less hassle with the props, better image quality, better range, equal or better battery life, more technology via sensors and modes.
Downside: gimbal is not as good and the wind will screw it up more.
ive had my mavics since the 2nd of December and have yet to fly them but have been wearing my phantom out and now my spark.,,only thing about the spark is in beginner mode is so slow i couldn't see using it.