Preorders: Sigma 28-70mm at BHphoto. Adorama. FocusCamera.

Photographyblog tested the new lens and concluded:

Overall, the new Sigma 28-70mm F2.8 DG DN Contemporary is a well-built, fast standard zoom lens that delivers excellent image quality in a very small, lightweight package.
It isn’t as good as our favourite Sony full-frame standard zoom, the Sigma 28-70mm F2.8 DG DN, in any aspect except size, but it does out-perform its main rival, the Tamron 28-75mm F2.8 Di III RXD, albeit at a slightly higher price-point, which makes choosing between them a close-run thing.

Dpreview also reviewed the lens and concluded:

If what you need most of all is portability and you understand the compromises necessary to achieve it, the Sigma 28-70mm F2.8 DG DN is hands-down the smallest and lightest of the bunch and still offers solid image quality.
It doesn’t hurt that it’s also among the most affordable F2.8 full-frame standard zoom options for the E- or L-mounts. For the size, weight and cost-conscious, it’s definitely worthy of consideration.

And here is Ted Forbes take on the lens:

Preorders:
Sony 50mm f/1.2 GM at BHphoto. Amazon. Adorama. FocusCamera. Fotokoch Germany. Calumet Germany, Foto Erhardt. ParkCameras UK. Jessops.
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Photographyblog tested the new Sony 50mm GM lens and concluded:

In short, if you don’t already have a 50mm prime lens in your camera bag, then this one should be at the top of your shopping list, as it’s simply the best 50mm lens currently available for Sony Alpha cameras.