JPEGs look very clean up through ISO 800, and there's a noticeable sharpness difference between ISO 800 and ISO 1600. ISO 3200 is usable, but I wouldn't recommend going higher than that unless you're willing to make some compromises.
The slighly polygonal out-of-focus highlights when stopped down a bit are the results of the lens' seven-bladed aperture; it's nice at f2.8. If you're picky about your bokeh, though, eight blades or more is better.
I had mixed results with highlight latitude on the Coolpix A. I couldn't recover any detail from the blown-out areas on the image on the left, but fared pretty well with the tablecloths on the right image. It performed well with shadow detail recovery.
The default Standard Picture Control seems to push contrast more than saturation, so there's no significant hue shift but some loss of shadow detail. The Neutral setting doesn't look too flat, though, which is nice.