Up to and including ISO 400, the GH1 produces relatively clean images. Though it's a bit difficult to see in this sample, there's a perceptible drop off in noise suppression quality between ISO 400 and ISO 800; if you look at the tape measure to the left of the "20" (as well as scattered around the text) you can see some of the yellow streaks that pervade photos at ISO 800 and beyond. Unfortunately, the noise tools in the SilkyPix raw software that Panasonic bundles doesn't improve much on the in-camera JPEG processing. You can also see the incipient problems in the nonuniform density of the text, where the yellow blotches get progressively more noticeable until ISO 800, after which the noise reduction gets aggressive.
At its widest, the 14-140mm (28-280mm equivalent) kit lens displays a bit of distortion, which looks as if is corrected in camera--note how the parallel lines get squeezed towards the left, but don't curve.