ive been a fan of the micro 4/3 platform since the GH1. The adaptability for it to almost accept most lenses if you already have some. The video quality is pretty good with the added size of the sensor over the old 2/3-inch ccds of camcorders a few years ago. the video controls feel particularly made well for doing video over the olympus brands 4/3 cameras and more functional then canons dslr(5dmrk3).
the main factors i looked at doing it for hak5 is I can get a great image, with a compact size, for a fair price point and controls i dont hate. It was the right camera for the job. (more television then film with Hak5)
The GH4 is particularly interesting because you get the advantages of 4k now along with some the other spec bumps of a new generation. It has all the stuff you would need to make great looking content.
Since 4k is starting to become more feasible as a fast production possibility but most content is viewed at 1080 resolution; I think it would be great as a single cam where you can crop and zoom to get two shots with one camera. Or if doing Film its great platform to if you know what you are doing.
theres a lot of cameras out there, just budget, the project and sometimes preferences show us what would be best to use. I would get a GH4 if I had the budget for it at the moment. But the GH3 are still great too.