From the very onset, the four thirds system was a mistake. The E5 was the last great camera to have graced the catwalks with that banner and both Panasonic and Olympus knew it would be the last.
Micro Four Thirds (MFT) lenses were smaller and cost less to build. Their form factor was taken from Olympus very own Pen-F, a half frame camera. The lenses too were of the same form factor.
The new EM1 is the pro spec line of cameras so it looks the part except that the size is more petite. Its ergonomics is just a tad bigger than the EM5.
Two NEW Features?
Seriously, I could not think of any other way to put it. The AF has been improved, it is even faster than the EM5 and there is a 'focus peaking' which is useful for fully manual control in macro shooting.
I am interested in the capture capability. video or still, but they don't add up with this new camera. Video still lacks 4K support, which the new Galaxy Note 3 has as a kick-ass feature.
Focus Peaking is used to estimate which zones of a scenes are in focus. Big deal. You probably find more uses for it if you are out in your garden trying to determine which insect you want to to be in your picture at the expense of that big lizard in the background.
Super fast AF? Cool. So how many of you got tickets to the Grand Prix? No? Then you won't need that 1/8000 sec shutter speed too.
What's the Damage Dude?
The older EM5 body alone sells for US$900, that's US$500 cheaper than the EM1 that retails for US$1400. Pixel for pixel they are both the same. The EP-5, which also sports the same sensor is priced at US$1000. That said, the EM5 is a mighty good deal today.
If WiFi is a big deal to you then go for the EP5. The EM5 doesn't have WiFi support but that can be remedied with an Eye-Fi card.