One of the main benefits of the moto G5S Plus (G plus gen 5) dual rear camera is the ability to capture photos with prominent DSLR-like background blur effect, like the one you can get when shooting with a DSLR camera and a bright interchangeable lens. The problem is with mobile phone cameras is that their sensor is too small and the lens is very closed to the sensor. The result is very narrow depth of field which result in the subject and the background being very sharp. The only way to get a good Bokeh effect is to shoot macro pictures, where you shoot the subject in a very close distance.
Here is a sample image that illustrates this effect. It wasn't taken with the G5S Plus, but it gives you an idea what more or less can be achieved.
Now with the Portrait mode (like the iPhone 7 dual-camera system), you have the option to take a photo where the subject is in focus and the background is very blurry. You can also benefit from post-focus adjustment, which allows you to chance the layer that you want to appear in focus after you have taken the image.
One of the main reason I purchased a digital SLR camera many years back (I think it was the Canon EOS 400D, my first DSLR camera) is exactly for that reason. I just fell in love with the Bokeh effect. I remember my father taking pictures of us in London when I was a child. I remember that photo like I saw it yesterday because it was so influential and probably had a very deep emotional effect on me. Me and my brother were sitting on a bench in one of London's street. We were in focus but the background was blurry. It was taken with my father's Nikon film camera with a 50mm f/1.8 or 50mm f/1.4 lens. I do remember the focal length, but not sure about the aperture.
Since then I felt in love with that artistic look in photos. Actually my first interchangeable lens for the Canon EOS 400D was a bright 50mm f/1.8 lens. It was a cheap lens, but it deliver exactly what I was expecting it to do.
I was very frustrated when I got my hands on many of the modern mobile phone cameras. I just couldn't achieve that effect, at least not when shooting a subject from an average distance, not in macro distance. The lenses in today's mobile phone are fast, but the sensors are just too small for that bokeh effect to be really prominent.
Things changed when dual-cameras came into the market. I also remember seeing apps that took several sequential shots and digitally process them to produce this effect with a single-lens camera, but it has its own limitations. Now with dual cameras like in the Motoroloa Moto G5S Plus (the one I am writing about now), the Moto Z2 Force, Gionee A1 Plus, Archos 55 Graphite, Vivo XPlay 6 - with all of those phones, and many others, you are capable for getting this stunning DSLR-like bokeh effect.
The thing is that you can even achieve a blur effect in a degree which is possible only if you purchase a very expensive DSLR camera and lens. Some can digitally replicate the effect of a f/0.95 aperture lens with a full-frame sensor, and trust me, that combo is very expensive and can cost you a few thousands dollars on its own. Of course the digital effect isn't in the same quality of its optical equivalent, but it's good enough for most users. It might miss sometimes and might lead to some weird results, but overall it does its job really well.
This is a must have feature for those who love shooting portraits. The reason why it's such a useful feature is because it allow user to capture shots with the subject in focus and putting the distracting background elements in the picture out of focus.
You can make some really artistic shots with it, and you don't need to be a professional photographer to make it happen. This is without a doubt one of the most noticeable advantage of the G5S Plus camera.