In May I decided to upgrade to an iPhone 7 Plus. I wasn't too excited about the idea of carrying a HUGE phone around, but I couldn't say no to the dual lens. It features a larger 1.8 aperture lens and an impressive megapixel sensor. I can't say that it compares to my full frame dslr, but it does justice for candid shots I take throughout the day (mostly of my cats).
Of course this feature is ideal for portraits hence "portrait mode." It also works for interesting depth of field shots involving any object in the foreground. You don't need a face for the feature to operate properly.