Dpreview posted the Sigma Quattro H review. The praise the ultimate detail you get at Low ISO but still..this is a “complex” camera to live with:
Overall, then, the SD Quattro H is Sigma’s best ever camera. This makes it easy to wholeheartedly recommend it to anyone already invested in the SA system and, perhaps for the first time, to suggest it’s worth a look for a broader audience than that. If you bear all the drawbacks in mind, it’s worth considering whether it’ll suit your type of photography.