I always found the portrait mode as a joke from Apple. I have seen some clones on Android that worked much better.One thing I can say about these betas: the 7 Plus portrait mode seems to have improved quite a bit. Much better IQ, less weird artifacts, sharper foreground, and it now seems able to achieve focus closer than before.
Plus the ability to turn off the background blurring effect after the fact (while editing the image.)
Well done there Apple.
The SW is doing a Gaussian Blur around the subject and didn't do a good job of determining the selection around the subject itself and started to do weird masking and very strange artefacts....
I will try it tomorrow to see if it did improve.