Rokinon, Samyang, Vivitar, Opteka, and Falcon, and maybe a couple others are all made by the same company in one of the Koreas and labelled under different names.
Even here, you have people who love the lens. Maybe I just got a bad copy.
I just read some reports about some problems with focus ring:
"Mine came with a miscalibrated focus ring (the lens was focused at infinite when it read 0.7 meters). Fortunately it was easy to fix (look on the internet for repair instructions). " (BH)
Ken Rockwell also writes about this.