In an age of huge numbers of megapixels crammed onto tiny, cheap sensors and stuffed into compact cameras featuring all kinds of add-ons like face detection, smile detection, baby detection, etc., the Sigma DP1 is a radical attempt to improve what used to be the purpose of a camera (and has now relegated to the level of a "feature" many choose to do without): image quality, as obtained by a photographer with his or her camera. The simple, elegant black box design features a large foveon sensor and can be made completely manual. There are dedicated buttons and dials for ISO, auto and manual focus. It doesn't emit a beam of light or beep to alert others of your intent to take a picture.
Out of the box, to an ordinary consumer, the DP1 is maddening, as it requires a basic knowledge of photography to obtain good pictures. Parents will miss shots of their kids, party-goers will be blurred, and soccer games will be frustrating. There is no real zoom. This camera doesn't do much for you.
For those who are able, however, it is an excellent tool to take advantage of. A photographer can adjust shutter speed and aperture easily, manual focus is also very useful. The shutter is silent. Focus is sharp, bokeh creamy. Latitude of exposure is actually astonishing. Experimentation is rewarded, one's style can be expressed, unhindered by all the bells and whistles the other compacts, the so-called "point-and-shoots" are burdened with. The DP1 is not just a subtle camera; it is a subtle reminder that those using it are going to be called upon to use their knowledge of light and shadow to make an effort to create photographs that express their vision.
Problems:
In that this camera does everything it has set out to do, I haven't encountered any problems. I would prefer a faster lens, but I'm sure the f4 was a compromise in order to allow for a relatively sane focusing speed for the large expanse of glass and sensor. Perhaps with advances in technology an f2 35mm DP2 will be next.