Allan Weitz posted this hands-on review with the new Sigma 14-24mm f/2.8 FE lens:

Designing an ultra-wide lens with low degrees of barrel and/or pincushion distortion is a challenge and, in the case of this lens, the results are mixed. At the longer end of the focal range, straight, vertical lines remain parallel to one another—even at the edges. As you zoom wider, barrel distortion starts to kick in. When shooting landscapes, this isn’t much of an issue, but for shooting architecture I would strongly recommend sticking to a better-corrected fixed focal length lens in the 12mm to 14mm range. However, for less critical work I would have zero considerations about purchasing this otherwise notable lens.

CamereLabs writes about this lens:

Sigma’s 35mm f1.2 Art has the largest focal ratio of any autofocus full-frame 35mm lens available. That bodes well for a nice Bokeh – and the lens certainly delivered the goods in my tests: its Bokeh is probably as good as it gets on a 35mm lens. Add to that the light gathering power that is a half stop ahead of lenses with a focal ratio of f1.4 and an optical performance that is always a bit better and you have the best 35mm I’ve tested so far. Add in thorough weather sealing with fluorine coating on the front lens, a de-clickable aperture ring, the focus hold button, and a well padded lens case plus strap and you get a well-rounded package that should leave little open to wishes. Unfortunately it’s also the largest and heaviest 35mm lens of the models I compared it against. But if you want the best 35mm lens for your full-frame Sony or L-mount mirrorless camera, the Sigma 35mm f1.2 DG DN Art is it. This also justifies its price and earns a Highly Recommended! Sadly it’s not available for other lens-mounts too.

And Photographyblog also tested the lens and writes:

Overall, the Sigma 14-24mm F2.8 DG DN Art mirrorless camera lens is a smaller, more full-featured update of the DSLR version that’s a strong rival to the Sony FE 16-35mm F2.8 GM in almost every area.

If you read chinese there is also a test at Fengniao.

New Sigma FE lenses::
Sigma 35mm f/1.2 FE at Adorama, BHphoto, Amazon, FocusCamera, Henrys. In EU at Calumet DE, ParkUK, WexUK.
Sigma 14-24mm f/2.8 FE at Adorama, BHphoto, Amazon, FocusCamera, Henrys. In EU at Calumet DE, ParkUK, WexUK.
Sigma 45mm f/2.8 FE at Adorama, BHphoto, Amazon, FocusCamera, Henrys. In EU at Calumet DE, ParkUK, WexUK.