As many of us are experiencing camera issue's (myself Included) I thought I would go back and check on the specs. I remember looking at them back in September 2016 at Mavic launch. I was resonably satisfied that in purchasing the Mavic that I would get reasonable (if not great footage)
Now I'm no expert in video but I do own a high end Nikon full frame DSLR but have never used it for video recording however I do at least have a basic knowledge about cameras in general.

Now like I said earlier I would not consider myself to be an expert but below I have listed Phantom 4 camera specs vs Mavic Pro Camera specs, now in my opinion there is nothing in the specs that suggest I would be seeing an inferior quality from the Mavic when compared the the P4.
The only thing that I can see the FOV on the Mavic is a lot less at 78.8 deg, now this should have no bearing on quality.

Any Experts out there?
Have a look and tell us what you see?

Phantom 4                                 Mavic Pro

  

  

Sensor	1/2.3” Effective pixels:12 M	1/2.3” Effective pixels:12.35 M (Total   pixels:12.71M
Lens	FOV ( Field Of View ) 94° 20 mm ( 35 mm format equivalent )     f/2.8 focus at ∞	FOV ( Field Of View ) 78.8° 28 mm ( 35 mm   format equivalent ) f/2.2    Distortion < 1.5% Focus from 0.5 m to ∞
ISO Range	100 - 3200 ( video ) 100 - 1600 ( photo )	100 - 3200 ( video ) 100 - 1600 ( photo )
Electronic Shutter Speed	8 s to 1/8000 s	8 s to 1/8000 s
Max Image Size	4000×3000	4000×3000
Still Photography Modes	Single shot    Burst shooting: 3 / 5 / 7 frames    Auto Exposure Bracketing ( AEB ): 3 / 5 bracketed frames at 0.7 EV Bias    Time-lapse    HDR	Single shot    Burst shooting: 3 / 5 / 7 frames    Auto Exposure Bracketing ( AEB ): 3 / 5 bracketed frames at 0.7 EV Bias    Interval
Video Recording Modes	UHD: 4096×2160 (4K) 24 / 25p    3840×2160 (4K) 24 / 25 / 30p    2704×1520 (2.7K) 24 / 25 / 30p    FHD: 1920×1080 24 / 25 / 30 / 48 / 50 / 60 / 120p    HD: 1280×720 24 / 25 / 30 / 48 / 50 / 60p	C4K: 4096×2160 24p    4K: 3840×2160 24/25/30p    2.7K: 2704×1520 24/25/30p    FHD: 1920×1080 24/25/30/48/50/60/96p    HD: 1280×720 24/25/30/48/50/60/120
Max Video Bitrate	60 Mbps	60 Mbps
Supported File Systems	FAT32 ( ≤ 32 GB ); exFAT ( > 32 GB )	FAT32 ( ≤ 32 GB ); exFAT ( > 32 GB )
Photo	JPEG, DNG ( RAW )	JPEG, DNG (Raw)
Video	MP4 / MOV ( MPEG – 4 AVC / H.264 )	MP4 / MOV ( MPEG – 4 AVC / H.264 )
Supported SD Cards	Micro SD, Max capacity: 64GB. Class 10 or UHS-1 rating required	Micro SD@trade;, Max capacity: 64GB. Class 10   or UHS-1 rating required
Operating Temperature	32° to 104° F ( 0° to 40° C )	32° to 104° F ( 0° to 40° C )

I've just noticed that the Phanton P4 does UHD: 4096×2160 (4K) 24 / 25p and the Mavic Pro does C4K: 4096×2160 24p.
So I went Googling UHD vs C4K and watched this on youtube, not a mention of quality just frame sizes really.

The short answer is there's not enough information available to properly compare the two cameras, the only useful information is that both camera sensors are 1/2.3in which is a small size typically used in compact cameras, superzooms, high end camera phones, action cameras etc.  so we know the Mavic isn't using a smaller sensor but as far as I'm aware, the exact sensor that's in use in both drones is unknown.  Even if it's the same sensor (despite the similar specs, it could be a different one) the processing behind the sensor can be quite different.  Raw photos are not completely unmodified files from the sensor, there's still some hardware processing first hence different cameras with identical sensors can produce quite different results even from raw files.

There's a couple PDFs floating around the forums that detail the Mavic's camera and sensor stack characteristics -- afaict the two major qualitative differences between them are the Mavic's shorter flange distance and the Mavic's sensor stack being unable to handle >30fps w/o throwing away data, resulting in lowered quality at higher frame rates.

This translates into the Mavic "hotspot" and the potential of aliasing artifacts in >30fps 1080 video.