Image quality, vignetting, flare and distortion test results along with specs, measurements and standard product images have been added to the Venus Optics Laowa 12mm f/2.8 Zero-D Lens Review page.
I think that you will like what you see. Here are a pair of comparisons you might be interested in:
Laowa 12mm f/2.8 compared to Canon 11-24mm f/4L Lens
Laowa 12mm f/2.8 compared to Sigma 12-24mm f/4 Art Lens
The Venus Optics Laowa 12mm f/2.8 Zero-D Lens is in stock at B&H | Amazon | Adorama.