This patch introduces a new navigation mode that is specifically designed for pen tablets, with sculpting/texture painting workflows in mind. Rotation is slower, panning speed takes the working area into account and the zoom speed is always predictable.
The main purpose of the 2D navigation mode is working with objects of a limited size, so it is not that convenient for navigating large scenes. When used in areas of Blender like sculpt mode, texture paint or grease pencil, it adds an extra level of polish to the user experience.
For comparison, this is the standard navigation using a pen tablet. Orbit around selection and trackball rotation are enabled.
After enabling 2D viewport navigation, the 3D viewport becomes much more smooth and controllable. I'm not pressing any shortcuts to reset the view or to set the pivot point manually.