Tried a lot of different DSLRs, the Sigma SD14 is in some respects my salvation.
IQ is the best I have seen yet. No need for much PP. Shoot RAW, convert it with SPP3(maybe a bit adjustemend - easy!) and be happy. It beats most other DSLRs into the ground.
No moire problems. That´s nice.
Pixelsharpness is very good, even viewing at 100 % is satisfying.
Build quality is ok. However, the covers for battery and CF feel a bit cheap. And the flash pop ups a bit too easy and feels not so robust.
However, I want to use my SD14 always when it´s possible. It´s a camera that produces excellent images when you know what you do.
I recommend to use +0,3 EV because the Sigma metering is very conservative. But better as if the highlights are blown out.
A good plus is that the camera has an AF assistance lamp. Only Nikon has this too. Canon or other manufacturers not.
Problems:
Slow write times on CF. Come on Sigma, 6 images with 3fps and then lockup was maybe ok with the Canon Digital Rebel / EOS 300D a few years ago, but not this days!
JPEG output is rather useless.
ISO100 and ISO200 are good, at ISO400 some noise begins to start. ISO800 is ok but other DSLRs are much better there. ISO1600 is very bad - don´t use it.
AF is slow. Don´t use C-AF. It isn´t able to track a subject. If you shoot most times with focus at infinity use S-AF.
No hard buttons for AF, metering and ISO.
Only one dial for shutter or aperture. Why not two?
Battery life only around 200 shots. That is ashaming for Sigma compared to the 1500-2000 shots I can do with my Nikon D40.
I would say this camera is a one trick pony. It has an excellent IQ, but bodywise it´s on the level of an Canon EOS 300D. So I have still a Nikon D40 that is more snappy and fast. And better for higher ISOs.
LCD is very bad.
And make sure to get a good Sigma lens. I had an 17-35mm that was decentered.
Overall I cannot say this is a camera I can trust. In critical situations I wouldn´t pick it up...