Low light sucks on GH4 - way too much moving noise with high ISOs, basically anything shot with out good light, pretty much sucks. Looking into getting a metabones speedbooster in hopes of it helping in this regard. But if you shoot in good light or outside it can be awesome. Also be careful taking advise on setting up the Profiles from Internet sources. Some are way off the mark. Cinelike D for post - Cinelike V for baked in look. Stay clear of bringing up shadows or master pedestal on camera - in most cases it just creates noise unless you have lots of light. Pans with 4k and punch ins - may not be the same as doing them physically but if you shoot with 4k sometimes things get in the shot you don't want - say if you were shooting a wedding and a wedding photographer walks into your shot. Saves the day when you can punch in - say to the bride in this case and then punch back out once the photographer is out of the shot. It is also the only way besides automation to get movement ( panning - zoom etc. ) in shots where the camera is unmanned or unwomanend. Focus is a consideration also - Can't fix Focus in post. So low light can be achieved on the GH4 but only when the Fstop is wide open which makes it even harder to keep things in focus. Dave Dougdale has a GH4 vs A7s video - the lack of Focus memory on the Sony is probably the only thing holding me back from purchasing a A7s. I have a focus puller on a GH4 that works really well - I can mark a focus then point somewhere else - focus - shoot pan back and pull the focus to my mark and it works perfectly. From what I can see on Dave Dougdales review the Sony is easy to focus with peaking but - maneuvers as I described above don't seem to work. Haven't tried this myself just going by his review. Would be interested to know if that is true or not.
I have had the GH4 for awhile now and my background did not include shooting video with a different DLSR so I don't compare the GH4 to other cameras. My opinions are only based on logic. Focus magnification during recording is a no brainer. You can't fix Focus in post - so while I am recording - checking my focus with magnification is a must. I realize also that there is no actual measurement view ( feet/inches etc. ) because there are too many different type of lenses and that would be impossible but one would think that Panasonic could figure it out for their own lenses. Focus Peaking is great but I find that it is sometimes really hard to see - my other camera is a CANON XF300 and focus peaking is very obvious on that. Another thing that bothers me is the ISO reading while changing ISO - you lose the exposure meter. So to see if you have added sufficient ISO for lack of light, - you have to change the ISO - hit the button again ( to turn it off ) then check the exposure. I only mention this as a bug because if you use the wifi app - you can see the exposer while changing the ISO. I have seen it mentioned in other forums but it has only come up once for me as a problem. The shutter speed when changing from stills to movie isn't remembered - I set my movie SS to 180 degrees and when shooting a few quick stills and switching back to movie mode the angle was all screwed up and had to be reset. Just annoying. Biggest problem is video noise ( dancing pixels ) in any video where there was not quite enough light ( basically any normal indoors shooting without extra light ) If the A7s could store 4k and have focus memory - it wouldn't even be close - I would never pick the GH4. People that rave about the GH4 usually throw in the value for dollar bit. I think we are at the beginning of new technology and competitors will outdo this camera - it's the old thing of sit back and wait or jump in. I know this well as I sit here trying to sell my Canon XF300 for less than half of what it was worth a couple of years ago.