I don't recommend going about ISO 200 with the S600; the photos start out looking a bit overprocessed (though noise-free), but at ISO 400 you start to see noise and some smearing, and by ISO 800 the smaller details are almost completely broken down.
There's some visible barrel distortion at the S600's widest angle of view, but it's not bad given the 28mm-equivalent focal length, and certainly no worse than the distortion we see on 35mm-plus-equivalent snapshot cameras.
Although you can see some pretty bad fringing in this example, for the most part the S600 didn't display much of a problem, even on extremely blown-out edges. I'm not quite sure why this photo had issues while similar ones did not.
The S600's images tend to be too soft, and the camera gives you no control over sharpness settings. Large prints look fine, though, as long as you don't plan to crop too closely or blow them up too big.