The GH3 has been my video workhorse for a year, and has made me shift from Canon to m43 for all video work. The image quality, the small size of body and lenses, the excellent integration of video into what is truly a hybrid camera, it's all great. It's pretty nifty as a stills camera, too, although I use other gear for that. I started m43 with the Oly EM-5 and loved it, but the GH3 gave me the impetus to shift systems for video.
The GH4 looks significantly better, but I intend to fully exploit everything I can about the GH3 before adding the GH4 to the stable. If that deal was available in Australia, though, I'd probably take it, as having a backup GH3, plus grip, battery and 25/1.4, could be quite handy.