I've had my DP1 for just over a year now. It fits into my shirt pocket.
I was immediately impressed with the image quality attainable with this little camera. In the year I have learned how to better use this tool, and how to work around it's much reviewed shortcomings. The more I use it the more comfortable I become with it and the more I like it. I don't believe It will ever be as comfortable and intuitive as my Nikon F, circa 1970, but it is more comfortable for me than any other digital camera I've owned, and it fits into my shirt pocket.
Digital cameras seem to fall into 2 general categories, point and shoot and DSLR. Point and shoots are small, easy to carry, slow to use and the image quality, although improving is not in the DSLR category. DSLR's provide great image quality but are BIG, noisy, intimidating and increasingly ridiculously expensive. The DP1 is the size of a P&S and shares some of their slowness. The camera does provide the ability to get around some of the slowness problems and delivers images that flat knock you out. I consider the image quality to be superior to my DSLR. Sigma has delivered a 3rd category of digital camera, available no where else as of yet. A high quality image maker that fits into a shirt pocket.
Perhaps the most written about shortcoming of this camera is it's slowness. Slowness seems to fall into 4 categories, “slow” lens (f4), slow to focus, shutter lag* and slow to write to the card.
*Shutter lag is most often a slow focus issue
Slow lens. A faster lens would be nice but not at the expense of size. In reality the f4 lens isn't that big a problem. My favorite DSLR lens is an f4 12 ~ 24mm. So f4 is the same. Also, without a mirror assembly to slap around causing vibration I can hand hold the DP1 at a much slower shutter speed. With the DP1 if “Continuous” shooting is selected 3 shots are fired dramatically improving the odds of a sharp image at a slower shutter speed. Finally although many DSLR lenses are faster than f4 very very few of them are as good wide open as the lens on the DP1. The lenses that are great wide open often have names like Leica or Zeiss and are wildly expensive.
Slow to focus & Shutter Lag. I had originally not understood why DSLR's had a mirror. It made no sense to me. As I researched it I found that auto focus doesn't work well at all without the mirror. The DP1 has no mirror and is subjected to the focus handicap. They are working around it and I am led to believe that the DP2 focuses much faster in low light. There is a really simple work around, manual focus. First however a brief operational review of auto focus with a DSLR. The Nikon I own has 3 auto focus selections. In 2 of them a failure to achieve focus disables the shutter...so I automatically lose the shot. In practice this is unusually frustrating to me. Also, I often photograph musicians in dimly lit clubs (flash usually). Quite often just before I release the shutter, or while I am actually pressing the shutter release, the camera will pick up something else, like a guitar string or something and change focus. I get back home to find strings in perfect focus but not performers. Not good at all.
Manual focus. I liked this camera immediately but really started to appreciate it when I took a minute to consider manual focus. This is a feature I believe that isn't offered on other pocketable cameras. The way this works is this: the lens has a quite remarkable depth of field, even wide open. I adjust the focus for more or less what I estimate the distance to be and the lens D.O.F. takes care of the rest. This completely eliminates focus lag and shutter lag. When I press it fires... instantly. It's quite simple and it works! For instance, f4 at 8 feet everything from 5 feet to 17 feet is in focus. f7.1 at 8 feet everything from 3.75 feet to infinity is in focus. How simple is that?
Slow to write to card. This is a real slowness that has no real work around. A faster card reduces write time slightly but it's still too long. I believe that this is something which could be fixed, here's why. The camera has a 3 shot buffer. When Continuous is selected 3 images shots are taken and stored in the buffer. The camera is “On-hold” after that for several seconds while it processes all 3 of the images. If only one shot is taken the camera is still on hold 'till the shot is processed even though there is obviously room in the buffer for 2 more images. Sigma! Don't close the front door to the buffer if there is still room for more images! Virtually all other digital cameras had the identical problem and fixed it! Get er done!
I've taken a lot of images with the DP1. Even with eliminating 2 out of 3 of the continuous images I take, and removing the poor images the Sigma file on my eSATA drive is 135 GB and contains 12,000 images. I'm guessing that's about half of what I actually took.
Customer service, excellent.
I have had to return the camera twice, once for dust and once because I damaged it. In each case Sigma had a brand new replacement camera in my hands exactly 1 week after I dropped it in the mail. The dust replacement was no charge. I paid for the damaged camera but it was VERY reasonable.
Damage: extending lenses are quite easy to damage while extended. I damaged the DP1. Sigma replaced it for $160.00 total charge. As a reference I had previously damaged my TVS111 film camera (extending lens). The repair cost me $180.00 + tax + S&H and although it's better it's not quite right.
Non removable lens. Quite a bit of chatter about this on the web. Some folks think this is a death sentence. I personally think it's whooey. As someone once said, if you have more than one lens it's a certainty the wrong one will be on the camera. I had my Nikon F film camera for 30 years and never really outgrew the 50mm lens. There is a lot to be said for having one lens that really suits you and learning how to work well with it. I have come to really appreciate wide angle perspective and although I might have wished for a wider lens I like this lens very much.
Also, Sigma appears to be planning a 3rd DP camera with perhaps a telephoto lens. I notice today that the DP1 is on sale for $350.00. Need 2 focal lengths, buy 2 cameras. The DP1 has a world class lens. A lens of that caliber is quite a steal for $350.00 and it comes with a camera attached. What you need then is a shirt with 2 pockets.