Image quality is very good, as I'd expected.
I noticed that if the scene is cluttered, it may focus on something other than the target object in low light, using spot focus on my Lumix G9. I'm still getting acquainted with the G9 so this might be my fault, but the 42.5mm f1.7 had no problem in the same light and same scene.
The lens mount is a very tight fit on my G9 compared with my other 4 lenses.
The lens hood can't be reversed and attached to the lens to save space when it's not used. It's not a fault but it will be an inconvenience.