I'd be happy to hear your list of competing third-party 85mm F1.4s. The only one I'm aware of is Sigma's, which costs a cool grand, more than three times the price of the Samyang. Samyang has become very popular lately for offering unique, manual-focus lenses for bargain prices. They really aren't competing with Sigma or Tamron - heck, it would be appropriate to call them a bargain-basement Zeiss or Voigtlander! I am looking forward to their upcoming 24mm F1.4.
Back to the original question - I don't have one but I keep looking at them. I hear that it's a bit soft at 85mm... which might be fine for portraits but I think I'd like a little more sharpness. The Sigma 85mm is "sort of" on the list but it's awfully pricey. I will probably give up a half-stop and go for the legendary Pentax 77mm F1.8 when I am ready to buy another pricey lens, which is a fair bit cheaper than the Sigma!
Really, though, the ~$300 Samyang 85mm F1.4 is quite a bargain; it's hard to be disappointed at that price, and you probably won't lose much money on it if you decide to turn around and resell it.