I've just been through an extremely frustrating experience with Panasonic. My most recent purchase was a Lumix G Vario 12-32mm F3.5-5.6 zoom. I added it my kit consisting of a Lumix GX7 camera body, a Lumix G 20mm F1.7, and a Lumix G Vario 45-150mm F4.0-5.6 zoom.
I've been pleased with the fixed 20mm and the 45-150mm zoom. All of my wildlife shots from our recent Africa trip (like these) used the long zoom, and they were very sharp.
But after using the 12-32mm zoom for several months, it became clear that it just wasn't sharp. I finally did tripod-mounted comparison shots with the 12-32mm and the 20mm, and the results were clear: the 12-32 is soft, both in the center and in the corners.
The lens was still under warranty, so I sent it off to Panasonic for service in November. After five or six phone calls (and none of the promised call-backs), and after sending in the comparison shot files, I was told that there's nothing wrong with the lens, and that comparing the 20mm with the 12-32mm was an "unfair" comparison. Bottom line: no repair, no replacement. They are sending the same lens back to me. Elapsed time: two months. Thanks for nothing.
I purchased the lens because it's small and wide-angle and had glowing comments on the Online Photographer. I've read that sometimes you just get a bad copy of a lens, and that zooms may be especially prone to variations in quality. I guess my luck wasn't good. But I expected better service from Panasonic. Caveat emptor, y'all.