fixing in post would not be something many would choose to do.
Exposure compensation before taking the photo would have produced better results.
I just didn't want to fiddle too much with the settings.
What I've noticed from comparing all the photos and examining their exif info is that the xperia s tends to use especially for indoor and lowlight shots, lower iso and slower shutter hence a lot of the photos come out slightly blurry or just out of focus entirely while the z2 opts for higher iso and faster shutter but still keeps noise under control at iso values 400 and below. OIS would help here allowing for lower iso and slower shutter.
In daylight, both devices generally use iso 50 for most shots and only use 100 to 250 late evenings and on very cloudy days with weak sunshine.
At night, the z2s iso is capped at 800 at full resolution but S went as high as 1000. Didn't do it much good because S really struggled with the night shots especially with focus.
I never use auto mode or shoot much at 8mp. The former can employ iso values as high as 6200 while the latter tops out at 3200. I can't imagine ever wanting to take photos using such a small sensor with such high values because they'll be full of noise and employing so much noise reduction that the resulting photo will look more like an oil painting than a photograph.
I just use the camera at full res because the iso range makes a lot more sense to me considering the very small sensor in play.
I'll be looking to do a similar comparison between the z2 and Z1 once I get it from a friend. It'll be interesting to see how closely matched or not both cameras are!