Either the dial or swiping can be used to navigate between screens. You access widgets right of the watchface and notifications left of the watchface. You can use the dial to select an app, a button on the side to take a step back or a different button on the side to return to the homescreen.
S2 runs Samsung's own Tizen operating system. It currently has a lot less apps than Android Wear or Apple's Watch OS and a lot of third-party apps perform badly on the device. It's unclear if developers will start to develop Tizen apps in the near future.
The smartwatch has a good selection of high-quality, elegant watchfaces. Additionally, Moto's app Connect allows changing background and color of different elements for these watchfaces (with some of them having additional, watchface-specific options).
There are two buttons on the side for navigation - a digital crown that you can rotate and press in and a simple, tactile button. While the button is pretty straightforward using the digital crown is not an intuitive way to navigate.