Like the DP2s, the DP1x is supposed to have a new faster processor, but there's little sign of it in the camera's performance. It takes nearly six seconds to start up and take a picture, and in single-shot mode and JPEG Fine quality the shot-to-shot time is approximate 2.6 seconds, about the same as the DP2s. Shooting in Raw mode it is slower still, taking progressively longer each shot as it waits to empty the buffer. In continuous shooting mode it can fire a burst of four shots (three in Raw mode) in just under two seconds, but then has to wait for over eight seconds for the buffer to empty before it can shoot again.
The DP1x has the same autofocus system as the DP2s, with the same set of problems. It's not particularly fast for a premium camera, and its low-light performance is terrible, failing to focus in light you could read by. There is no AF assist light, so low light shooting has to rely on manual focus, but with such a small monitor and no view magnification this is virtually unusable.
If you read the article linked at the start of this review you'll know that the Foveon X3 sensor has three photoreceptors at each pixel-point on the sensor. Because of this Sigma insists on referring to it as a 14-megapixel sensor, but this is rather disingenuous. The final image size is only 2652 x 1768, or 4.7 megapixels. Sigma's big claim about the Foveon sensor is that it produces better colour depth and sharper detail than an equivalent conventional Bayer-mask sensor. This is certainly be true; there's no question that it produces vastly superior image quality to a conventional five megapixel sensor. Unfortunately nobody makes five megapixel sensors any more, and haven't since about 2005, about the time that the sensor in the DP1x was developed. If you compare the DP1x to a modern 12 or 14 megapixel compact, or even to the 10MP 1/1.7-inch sensors used in most other advanced compacts, the Foveon sensor's image quality advantages are simply no match for more up-to-date technology. Looking at the sample images from the DP1x it's easy to be impressed by the sharp detail and excellent colour depth on a computer monitor, but if you want to print them out at 300dpi photo quality they're only big enough for an A5 print.
The lack of resolution isn't the only image quality problem. White balance is very inconsistent, varying in consecutive shots under identical lighting conditions, and image noise is also a problem at all sensitivity settings above 100 ISO, with visible banding on shots at 800 ISO. Dynamic range is also quite limited, especially under strong backlighting.
The DP1x is Sigma's attempt to squeeze the last bit of mileage out of a five-year-old sensor design. While it can certainly take a very good picture under the right circumstances, it is beaten soundly on features, performance, handling and image quality by cameras costing half as much.