The DP2's photos remain quite sharp across the entire ISO sensitivity range, and the color noise patterns are quite subtle and pleasing.(You can only shoot ISO 1,600 and ISO 3,200 in raw, which, in turn, only supports AdobeRGB, so the higher ISO shots will look a bit flatter than normal.) However, the camera has unusually poor color consistency across the various sensitivities, even at the low end.
The DP2's high ISO photos stand up well to noise reduction. You can see there's virtually no color noise, while it still retains a fair amount of detail and little or no graininess. The photos do tend to get desaturated at the higher ISOs, however, starting with the greens. (ISO 800, f4, 1/400 sec, Adobe Camera Raw default settings. The ACR settings seemed to produce a similar image as from Sigma's raw processing software. You can probably get slightly better results with more tweaking.)
Here the desaturation and slight bit of color noise becomes more prominent, but there's still a reasonable amount of subject detail and depending upon what you're shooting and the effect you're going for, the photos can still be quite usable. (ISO 3,200, f4, 1/800 sec, Adobe Camera Raw default settings. The ACR settings seemed to produce a similar image as from Sigma's raw processing software. You can probably get slightly better results with more tweaking.)
Because of the lack of an antialiasing filter on the sensor, the DP2's photos look quite sharp. Our sharpness tests place the camera's performance on par with that of an 8-megapixel camera with a good lens; not quite as good as Sigma's claim of 14 megapixels, but far better than you'd expect of a sensor with a spatial resolution of 4.7 megapixels.
For a lens with a physical focal length of 24.2mm, there's surprisingly little distortion, and it's pretty symmetrical. (This is underexposed; I had better exposures but they were all slightly skewed.)
The Sigma DP2's default Standard color mode isn't quite as bad as that on many consumer cameras, but it still results in some color shifts. You can't change the settings for any of the presets (or even know what the exact settings are) but you can increase or decrease contrast, saturation, and sharpness for any of them, via a separate setting, in +/- 5 steps.
The Foveon sensor renders fine patterns with no moire. And the fine-grained appearance of noise makes the camera a natural for shooting very film-like black and white photos. (ISO 800, 1/50 sec, f2.8. I've got the contrast cranked up a bit here.)
The DP2's white balance is excessively cool; those geraniums in the upper left corner are actually an eye-burning red. (All shot in Neutral color mode. Our lab tests were shot in the default Standard mode. Neither yielded particularly accurate colors.)