Update: It looks like DFD does not work with older 4/3 Panasonic lenses. My GH4 came in 2 days ago and the performance of the 14-50mm on the GH4 is no different than my GH2.
Quality wise, the 14-50mm is pretty stellar in my opinion. The sharpness is there when recording 4K on the GH4, as the sensor is using more of the center of the lens due to the 2.3 crop.
Here is a sample of a few shots I took while on my lunch break. I wanted to test out the resolution and codec when recording highly detailed subjects, gravel, leaves, running water, lines from architecture.
All clips were shot in 4K@30p and edited into a 1080 30p sequence in Premiere Pro CC 2014.
In Premiere each clip is shown at 50% and 100%.
Half of the frame is graded to show what the CineLike D color profile looks like when a slight RGB curve is applied in post.
Vimeo's compression pretty much destroys the detail, way too much macro blocking, download the original clip if you want to see the insane amount of detail this camera can deliver.
Camera Set up:
GH4 with Panasonic 14-50mm f/2.8-3.5 Leica D Vario-Elmarit Aspherical MEGA O.I.S. Lens
4K 100mb 30p, 3840x2160
CineLike D: All at 0.
ISO 200