I read in one review of the lens that it had 'huge vignetting' but I wouldn't say overall on all those it is a 'huge' issue. There are dark corners on 3 but I don't know if that is vignetting or the natrual effect of the light. The 4th has what looks very much like vignetting.
What's your opinion on that?
That's some seriously nice work. I think Panasonic hired you to show off their lens because those photos have almost nothing to do with the equipment!