It's easy to learn, and it took me about two hours on a weekend to learn . And, easier still to use in designing and visualizing architectural interior designs.
SketchUp is strictly a 3-D tool. SkecthUp uses a separate application to view the design in 2D, called "SketchUp Layout". It comes with the SketchUp free download (for one month), but it opens with a separate thumbnail.
The kicker is, SketchUp Layout cannot manipulate the converted 3-D data from SketchUp. SketchUp transfers the original data into Layout as JPEGs.
So, for instance, say you want to dimension a floor plan, created in SketchUp, and export it to a .dwg. This file will not be editable by AutoCAD or any other CAD software that reads .dwg files. It will read the data, but that's it. You cannot shift a wall or move furniture - even if you explode the data (the images are deleted).
Regardless, many architects have chosen to ditch AutoCAD and Revit, which can be very user-unfriendly, and instead create construction documents in SketchUP.
We leave you with this analogy: "SketchUp is to Revit, as Fusion 360 is to Inventor?"