Image quality, vignetting, flare and distortion test results along with specs and measurements have been added to the Samyang 16mm f/2 ED AS UMC CS Lens (also branded as Rokinon/Bower) page.
Looks like a decent lens from an optical perspective. Full disclosure: we returned our first copy of this lens due to a misalignment issue.
B&H has the Samyang 16mm f/2 Lens in stock.