Sony's focus peaking, probably not the best solution for critical focus:
http://theonlinephot...us-peaking.html
In my opinion, Sony camera's look better in the specs department than they perform -- it's a marketing advantage, not an advantage for photographers.
24MP might seem like it offers a lot more resolution, but the Sony comes with a stronger anti-aliasing filter (which destroys resolution). The AA filter on the OM-D is very weak (Olympus uses industry-leading software for JPEG users that minimises moire, but RAW shooters get ultra sharp images due to the weak AA filter). Also, 24MP only offers a 22% increase in linear resolution, not the 50% you might expect by looking at the specs.
I also believe that Olympus leads the way in EVF focusing downsampling. EVF resolution is not the main determinate of being able to critically focus on the unmagnified EVF, the software that downsamples the sensor for the EVF determines how well critical focusing can be performed, and here again Oly appears to lead the industry, allowing critical focusing without resorting to magnified view even with f/0.95 manual focus lenses at very close distances.
Also with Nikon, Olympus and Sony sensors all made by Sony, the differences between sensor design and capabilities are diminishing. One thing that we know, for sensors using the same technology, the difference from M43 to APS-C is only 1/2 the difference from APS-C to full frame (that's because sensor area goes from 1.0 for full frame to 0.39x for APS-C to 0.25x for M43.) Or, in other words, there's a 4/3 stop difference between full-frame and APS-C and a 2/3 stop difference between APS-C and M43.
With Sony going to a base ISO 100, the dynamic range and high ISO performance of newer Sony sensors is exactly the same as the OM-D from ISO 200 up. The Sony's typical 1/160 flash sync speed, vs the OM-D's 1/250 unfortunately means the Sony can't quite benefit from the ISO 100 for underwater photography.
Lastly, as a compact camera system, the lenses for the APS-C sensor NEX cameras are just too large for the body. Just compare Sony's 50mm f/1.8 portrait lens against the Oly 45mm f/1.8 portrait lens in a shop sometime. You'll also probably never see a macro in the 90mm-150mm full-frame equivalent range, simply because it would be too large for the body (that's why Sony make a 30mm macro -- it's a more reasonable size for the body.) Oly has an ultra-sharp 2:1 equivalent, 120mm equivalent macro. Also you don't find much fast glass for the NEX -- again it's too large for the body, whereas for the OM-D, there's a lot of fast (and sharp!) glass. While Sony lags in the lens department, that lag will be permanent because it doesn't make sense to make such large lenses for compact camera system (if you're going to carry around several APS-C size lenses, why not just carry around a more ergonomic APS-C DSLR, the total size difference just isn't that great.)
