The SIGMA DP3 Merrill is equipped with a hot shoe, allowing use of the dedicated external flashgun EF-140 DG (optional) as well as SIGMA electronic flashguns for SD series such as EF-610 DG Super (optional) and EF-610 DG ST (optional).

ENGADGET: Sigma DP3 Merrill packs a Foveon X3 sensor and a fixed F2.8, 75mm-equivalent lens

The much larger sensor and superior processing gives you massively better image quality, they're much faster (with little or no lag) so better for action, there's a lot more creative control over things like depth of field, the option to change lenses, add flashguns etc add to creative possibilities and also increase image quality.

BBC: Tips for picking the right camera