I recently bought a GX9 which comes with a general lens, non-prime 12-33mm / f3.5-5.6. It was not giving me the results I needed for ghe style of photography I do.
This lens is brighter and sharper, and at 20mm it feels not unlike a 50mm lens on this camera. The softs are soft and creamy and the focus is pin sharp. It has transformed the camera for what I do.