Never used it before, but just downloaded it for the Gear S. It then prompted me to download it on my phone, but even before I signed up for an account on my phone, it was ready to track my run on the watch.
Out of the box, without a phone connected to it, it is preset on running (someone please confirm), and it has three preset screens or "Views", that you can swipe right/left to see:
View 1: duration, distance and speed.
View 2: Calories, pace
view 3: HR
If you connect the phone, in the app, you can select your device under settings (support for Gear S indeed), then set up what you want to see on the three different Views for the watch - each View has three zones that you can assign a metric to.
Let me know what else you need me to test exactly, and I'll do it.