Mediocre and slow for video
I got this lens as kit with a new GH3 for event videography which was a mistake. I'm shooting 1080p and it' can't find focus in (relatively) dark rooms even when the light is in the ISO 1600, 1/50, f/4, level where even the little NEXes don't have a problem focusing. It searches a lot and makes footage unusable when using Continous AF. I know I should be using manual focus, but the GH3 doesn't support MF assist in video mode! Talking of Catch 22 situation. So, it's an overpriced and not satisfying combination for run & gun and event videography.
The image quality is fine esp. in the wide to middle range. Also focus is fine in bright sunlight.