Overall image quality produced by the S570 is very good and is actually one of the better recent Coolpix cameras I've tested. The camera lets you limit the auto ISO to either 80-400 or 80-800. If you're shooting outdoors or in a brightly lit room, I recommed putting it at 80-400. The S570 did perform well up to ISO 800 with minimal color shift and most fine detail intact, but it's at its best below ISO 400.
It can shoot at full resolution up to and including a sensitivity of ISO 3,200. However, both it and the step below, ISO 1,600, don't look good because of color shifting and yellow blotching. So while you can, in fact, keep shooting in low-light conditions, I can't say you'll be thrilled by the results.
Colors are not accurate from the S570, but I can't say I'm disappointed with the results. Everything turned out nice and bright and reasonably natural looking.
The picture of the Flat Iron Building in the lower right was adjusted using Nikon's D-Lighting option in Playback mode, bringing out details lost in the shadows of the left side of the building.