Image quality results from the Canon EOS 5Ds R, Canon EOS-1Ds Mark III and Canon EOS 7D Mark II have been added to the Samyang 14mm f/2.8 Lens (also branded as Rokinon, Bower, etc.) page.
The first comparison I wanted to see was the Samyang 14mm f/2.8 vs. the Canon 14mm f/2.8 L II Lens. The second was the Samyang 14mm f/2.8 vs. the Zeiss 15mm f/2.8 Lens. While the Samyang comes up short of these other two lenses from an images quality standpoint, it is a FAR lower-priced lens. Stopped down modestly, many are going to find the lower price to more than offset the modestly lower image quality. Especially those who only infrequently need a focal length this wide will find the Samyang a very attractive option.
A full review of the Samyang 14 is planned for the near future.
B&H has the Samyang 14mm f/2.8 Lens in stock. Note that the Nikon mount version of this lens is $50 more expensive than the Canon mount version, apparently due to the addition of a focus confirmation chip. Prices for other mounts vary.