Bryan at The Digital Picture has completed his review of the new Sigma 24-105 f/4 DG OS Art series lens. This lens retails for around $899 USD, and by the looks of the review, that's a bargain of a price. This lens has already begun shipping for the Canon mount.
“I've tested a lot of lenses that made me anxious to move on. This is not one of them. I would have no problem making this my primary general purpose lens.
The Sigma 24-105mm f/4.0 DG OS HSM Art Lens' long focal length range will take a broad swath out of your angle of view needs. This great-looking lens is a joy to use and the results from it are even exciting to view. For a reasonable price, the Sigma 24-105mm f/4.0 DG OS HSM Art Lens reliably delivers the excellent image quality you are looking for from your DSLR camera.”