Sigma has always made some very interesting cameras that in many ways felt like they shot themselves in the foot, and something like the Sigma sD Quattro I believed to really fix a lot of the problems of previous cameras. To start, the camera offers two models: an APS-C model and one that moves away from APS-C sensors and went to APS-H–a dead standard that Canon used to include with some of their 1D series cameras. The sensor has a 1.3x crop factor and so is larger than typical APS-C sensors. It still uses a Foveon sensor, which in the hands of a skilled editor can produce some absolutely flawless results.
And unfortunately, the autofocus is still stuck in the early 2000s.