The Samsung Galaxy S8 features a Pro Mode for its rear-facing camera. This mode gives users a full control over the camera settings when composing your shot. You can control six different camera settings and set them as you desire. This includes the ISO sensitivity, shutter speed, exposure, color tone, white balance and you can even change from autofocus to manual focus to adjust the focus manually by yourself, instead of relying on the autofocus system to do it.
Before I move on talking about why you want to have a pro mode in the Galaxy S8 and what it gives you, let's take a look at a video taken by pocketnow that showcase the Galaxy S8 camera app interface:
The Pro Mode gives users a way to take more creative shots. The auto mode is designed to do its best to take a sharp image and making sure that your image look well exposed and sharp every time. Of course there are some scenes that the Galaxy S8 will struggle to shoot at, for example, if you are shooting at a pitch black scene, no camera settings will help you get a good photo in that type of scene. The Pro mode was made to allow users to achieve particular results that otherwise they wouldn't be able to. For example, forcing the S8 primary camera to intentionally shoot at base ISO and slow shutter speed to get a blue effect of motion in the photo. Another option is to set the white balance to a different one that the camera would have used in auto mode to make colors appear warmer in the photo.
The Auto mode isn't a magic mode, sometimes it might give you results that you don't want to get. It can be restrictive to some photographers who want to capture images different than what a conventional point-and-shoot camera would do. Having the option to fine tune those camera parameters while seeing the results live on the screen is a god sent for enthusiast photographers. I'm used to do it when I shoot with my Fujifilm X-A2 mirrorless camera. In fact, I almost never shoot in auto mode at all because I've got used to shooting in manual mode. Even with my Galaxy S7 i mostly shoot in manual shooting mode, not auto.
For many people the auto mode will be the preferred shooting mode of choice, because you just need to to tap to focus and capture the shot. The Samsung Galaxy S8 will obviously do its best to make sure the image looks great. This Pro mode is there for you in case you need it, or at times that you feel that you would have preferred a particular image to look different than what the camera is shooting. Then you can just switch to Pro mode and adjust the settings for yourself and get that scene to look the same as you want it to look in the photo.
So having a Pro mode is a great advantage for enthusiast photographers who want to be more creative with their Galaxy S8 phone camera.