Bakewell wrote in post #16441880
You left out probably the most important difference...being disposable...hope you don't have a major problem or into the trash it goes! You can rationalize all you want. Pick and chose to your hearts content. This is important and that isn't. BUT all are legitimate reasons for picking the 14L. Did I mention NO weather sealing, No gel filters, No exif data on the Samyang/Bower/Whatever. My point is there are MAJOR differences.
Wow, someone seems little cranky today. Maybe you seem upset that people seem to get same results than you with five times cheaper lens? And I mean no disrespect here. I just think you are seriously underestimating the Samyang here. There is a reason why the Samyang is so popular on these boards and the Canon is not that popular. Results speak for themselves.
Bakewell wrote in post #16440790
Distortion...Manual focus...Disposable...Freakish looks
But ok, I bite:
Image quality: According to TDP
and DxOmark
the IQ is very similar. Basically both lenses are just as sharp. Not bad for five times cheaper lens, eh? Note that DxOmark actually rates Samyang higher.
Distortion: The Samyang has more distortion. True. But is so sharp it's easily one click away from beeing fixed in Lightroom/Photoshop. Not a problem.
"Disposability?" What does this even mean?
I am not even sure I would call it a win for Canon. According to Lensrentals
the 14mm f/2.8L II 7th most likely lens to fail. It's surprising because the Canon is so expensive lens and Canon offers only a lousy 1 year warranty. Never liked Canon's warranty policy. It's true it is extremely unlikely that any lens will break down, but since you are the one who brought the term "Disposable" I thought this should be mentioned.
Samyang has had 1 main problem: distance scale does not match real distance. Not a big deal as it's so easy to focus. But in the same time Samyang is five times cheaper and offers 3 years of warranty. So, even if the Samyang breaks down or you get a lousy copy you are more than likely to still be covered by Samyang's warranty if it somehow magically breaks. For free. Unlike the Canon, which repairing it would probably cost just as much as a brand new Samyang. Or where I live, you'd get probably 2 Samyangs for the same price for repairing the Canon. Shocking.
Weather sealing:
Canon has weather sealing. Samyang does not. However, one should remember that no lens truly becomes weather sealed until you mount a filter to complete the sealing. And the Canon does not accept filters so it's bit misleading. I also wanted to mention that I used the Samyang in really horrible conditions (storm, rain, cold, winter, snow) and it still works like a charm.
Freakish looks: What?? I think the Samyang looks very sexy. You can always glue a red ring if that seems to turn you on 
Focus: Canon has autofocus. Samyang does not. But using a UWA lens who even uses autofocus? I would never trust autofocus when making critical focus on landscapes. Even if I had autofocus in my Samyang I would never use it. Focusing this thing is so easy. Set f/8 and the whole scenery is basically in focus. It's almost as easy to focus wide open as well.
Exif: Samyang does not report EXIF. Canon does. If this bothers you, you can get a chip and glue it on the Samyang. It will cost you $10 and it will take ~5 minutes and you are done. I did it and it's not a big deal.
Price:
I just checked the cheapest prices for both lenses where I live. The Samyang is no less than 6.1 times cheaper 


I guess this is my main dilemma here. For the same price as the Canon you can get the wonderful Nikon 12-24mm f/2.8 or the magnificent Zeiss Distagon 15mm f/2.8 T*. I know which lens I would choose instead. But that's just me. An other interesting thing: Canon recently released a patent about Canon EF 14mm f/2.8 L mark III. It seems Canon is already working on a replacement for this lens?
So the answer is no, the 14 II is not clearly superior in EVERY respect. But I'm still glad if you are happy with your investment. 