The Pen tool is incredibly powerful, but not always the easiest to use for newcomers. Even those familiar with other Photoshop features are often less proficient with using the Pen tool to select specific areas or create paths. While it's not meant to replace the original Pen tool, the new Curvature Pen tool previewed in this video helps make a faster and more accurate selection around objects with curved edges in a way that could even be faster for those who are already good with the traditional Pen tool.
The new Curvature Pen tool also seems great for creating shapes, but it's unclear how great it would be for outlining complex shapes with many varying curved and straight edges. This is likely why the Curvature Pen tool is seen as an additional, helpful tool to complement the ever-dependable Pen tool.
At the end of the video, Adobe explains this is a feature that will be available at the end of the year with a new, major release of Photoshop CC. Perhaps we can expect a few more sneak peeks before we get there.