Image Quality
Let's start with the most important. Here we have the first time a (m) ft camera that also allows relatively strong lifting the shadows in the image processing, without noticeably noisy. The color noise is absent in the lower ISOs completely. Who reworked his paintings like (intensive), now gets a clean foundation with a lot of leeway in the shadows even when MFT.
But the lights are now so stable that the best (Sony) APS-C sensors is no longer any difference. The E-M5 yet produced out of cam-contrast images and punchy without the lights burn out early.
Along with the most above average rand sharp images, you get to the E-M5 camera, in my opinion, ALLEN APS-C cameras covering the whole chain is superior (lens - Output - sensor). What the E-M5 with the Panasonic 25mm 1.4 produces to crispness and sharpness even at full aperture to the edge, leaves a NEX7 with the currently best NEX Lens 24mm look plenty old. Not to mention the Panasonic 7-14, despite the digital correction even any combination of small picture (or marketing pregnant often called full-frame) and wide-angle zoom beats.
From point of view of image quality, there is little more real benefits for small format. APS-C turns out now as a dead end, it always was, what one sees, especially to the enormous compared NEX lenses, of which so far no one comes close to the focal moderate counterpart in MFT.
Handling
For my midsize men Hands represents taking pictures with the E-M5 is a challenge. Everything is Arg delicate and confined space. Together with an adapted 14-54 MKII camera without the HLD-6 battery grip is not really easy to operate. With lightweights like the 45mm 1.8 is, however, no problem.
Otherwise, the HLD-6 is recommended. But the landscape of the grip HLD-6 (which is separately mountable) relieving the right hand noticeable and makes the grip and hold securely.
The additional Eyecup E-P11, however, is a joke. In the glasses you're so far away from the viewfinder image that you do not have anywhere near complete insight more. Even without glasses, the vignetting is too high. In short, the E-P11 you can save. The normal supplied eyecup is great even for eyeglass wearers.
Autofocus
Olympus claims it has become even faster. I can not tell the difference with the best intentions for E-P3. Even the adapted 14-54 MKII is not faster at the E-M5. It may be that especially the new 12-50 rausreisst and some real Nachführfokus especially with video allowed. Can I myself do not consider, as I do not prefer this lens alone due to the lack of light intensity into consideration.
On the subject of C-AF I can not say anything because I do not use the for my photography.
The Image Stabilizer
In a word: WOW! Yes he rushes something that is weak wahrnembar in very quiet environments, micht but does not interfere. For that, I'm just excited about the stabilization. Just to have a completely stabilized viewfinder image, designed manual focusing with old lenses to were child's play. Especially with some old OM lenses that a "jumping" have focus, you can focus accurately even without viewfinder thanks to the stabilized viewfinder image. I thought so far, Olympus should implentieren similar Sony peaking, but manual focusing is now so precise that I do not miss peaking.
Otherwise
The display is already at the top, such as E-P3. Now it is also foldable and therefore photography is from all angles possible. The reaction speed of the touch screen is like Iphone and so much better than a GH2 or G3 Panasonic. Ever is the E-M5 just like already the E-P3 to worlds faster than the MFT Lumix cameras: The buffer is larger, the camera writes faster card, the flash is charging to faster etc.
For studio flash strobist owners and should be interesting that the E-M5 is synchronized along with the Phottix Strato II and Bowens Gemini 400 or a FL50R without grumbling 1/320. 1/250 makes them anyway out of house and is thus superior to many APS-C rivals. Not to mention a GH2 or G3, with whom you can not even shine through in burst mode.
Conclusion
A lot of wood does the E-M5. Without Doubt. Who does not need the last bit of image quality, etc. is also well served with an E-P3 / E-PM1. The G-Series of Panasonic's top, although I do not like the color reproduction. But is a matter of taste. Who is willing to invest in this price range, can engage without concern for E-M5. To touch more on resolution and the Qäntchen more high quality Iso a Nex7 is more than outweighed in the E-M5 by: lengths to better AF, across the board looking away better lenses and a stabilization of his peers.