DXOMark has completed their review of the Samyang (Rokinon/Bowers) 24mm f/1.4 for Canon. The lens gets a pretty good review, especially when you consider the very good price of $669. When compared the Canon of the same focal length and aperture, you're paying an additional $1100 for AF and a better performance wide open.
“Although the Samyang is a phenomenal performer, when stopped its sharpness wide open doesn’t match that of rival high-speed designs. Given the modest pricing it will no doubt continue to be a popular model but it would be all the more attractive with the addition of automatic aperture control and perhaps AF-assist (though it’s often unreliable without experience). There’s another, often overlooked benefit from the inclusion of data transmission – EXIF data stored in Raw files could be used by third-party software suppliers to apply lens corrections. Future updates such as these would seem likely but for now the Canon mount version is overshadowed by the better performing rivals.” Read the full review