One thing I noticed in my testing yesterday was the different "look" of the GH2 files when imported into Photoshop ACR for raw conversion. They seemed to have a "flatter" lower contrast look. Dynamic range has always been a problem up to now for m4/3, but I think Panasonic have gone some way to improving it.
All the images in this post are converted from raw with all the parameters in ACR in Photoshop CS5 "zeroed out" I've added the histogram to the picture. You can clearly see the headroom at the highlight end. There's a lot of shadow detail too.
As ever exposure is critical here. Its easy to moan about a cameras dynamic range when you either over or under expose, and its really important to get the exposure right to retain the maximum amount of information available in order to work on the file later, where increased contrast and overall "punch" can be added.
Certainly Panasonic claimed that they had increased the dynamic range when they announced the camera and though only using the camera for a day it looks to me like they have.
DxO Mark claim the GH2 has a "worse" dynamic range than the GH1. However I'm extremely skeptical about DxO "results" since they don't offer any examples or say what they are measuring.
As ever I use my eyes for my own assessment. Right from the first picture I took with the GH2 I did notice this lower contrast.
This is of course incredibly useful and deals with one of the problem areas of m4/3. I will be looking at this again as I use the camera more to see if it is as good as I think it is.