At all ISO sensitivities, Ricoh seems overly aggressive with the blurring aspect of its noise reduction, and there's serious aliasing on edges. I wouldn't recommend shooting JPEGs at anything higher than ISO 200.
Here you can really see the edge problems--look especially at the eyes and the fine grid pattern that appears in the shadows. In the latest firmware update, Ricoh added a Max noise reduction option, but as far as I can tell that just increases the blurring even more.
(1/30 sec, f2.8, AWB, evaluative metering, Neutral color)
The GXR's in-camera distortion correction is relatively subtle, partly because there isn't much lens distortion. The slightly different framing is not a correction artifact, but the differences in white balance seem to be.
(1/125 sec, f4.4, AWB, evaluative metering, ISO 100)
Close up shots look just a smidgen soft when zoomed in, but this is the kind of softness that can stand up to some sharpening in post process.(1/290 sec, f6.1, AWB, centerweighted metering, ISO 100, Natural color)