While a photo's fine details look OK at middle ISO sensitivities, it's generally because in its default settings Samsung applies excessive sharpening. As a side effect, though, artifacts get exacerbated in areas that might otherwise exhibit little noise. For example, note the very visible color noise and the blotchy luminance noise patterns here.
(1/125 sec, f8, evaluative metering, tungsten white balance, ISO 400, 18-55mm lens at 45mm, default JPEG settings)