So my two cents on the iPhone 7 Plus “Portrait Mode”…While it does a good job of mostly recognizing the subject that needs to be in focus and blurring out everything else.
By not means its perfect, the software still has issues recognizing which parts should be in the same field of focus and which objects need to be blurred that are/aren’t part of the subject.
For example this photo notice some of the brush is in focus that is CLEARLY not part of the subject. Also notice that the bush that’s in front of the subject is also perfectly in focus. In a perfect world 90% of the brush should be blurred or out of focus, Except the brush that in the same line of field of focus.
Also it does a terrible job at recognizing fly away hairs or other thin, sharp or small objects that are part of the subject that should be in focus and just completely blurs it.
It’s a cool feature to play with it but still has major work ahead. I rather just stick to the non-portrait mode and just use that second lens that similarly to a 50mm lens.
In conclusion just stay away from “Portrait mode” unless you want your photos to look like a bad Photoshop job.