I was curious as to how the new ISO 100 feature would perform. I didn't expect better/cleaner resolution as ISO 200 is the native level for the sensor. The ISO 100 setting is called "Low", not ISO 100. Whereas above ISO 200 it says "Recommended", above "Low" it says "Extension". I took some shots outside with my 12-40mm and my new 9-18mm lenses. I was shooting in Aperture priority mode and all my photos taken at ISO 100 were consistently taken with 1 stop slower shutter speed as expected. What I consistently found with either lens was that the ISO 100 setting resulted in about 0.5 stop overexposure (as measured by adjusting the exposure until histograms looked similar). There was also a very slight decrease in contrast at ISO 100 vs 200. Those are the only differences I saw in my quick test.