Summary: This lens is the pinnacle of technology and optical quality for portrait artists. Though a bit on the heavy side for use on mirrorless A7R but I have not taken this lens off my camera ever since i received it. Images are rendered beautifully and the bokeh at f/1.8 is amazing. The image center is very sharp when used wide open and creates incredible pictures.
Summary: I bought this lens in mid December, 2013, and I have been stunned by the quality of the photos I have taken with it. It took some getting used to. It is big and heavy, but I love that about it. Sometimes it doesn't focus quickly enough and occasionally it tends to hunt in very low light, but with this lens, when you nail a shot, you knock it out of the park!!! I love it and I use it every chance I get.
Summary: I'm not jumping on the bandwagon with this lens because its a Zeiss. I have used this lens a couple of times with mixed results. I had taken this lens out one day and popped it on my A77 for a Parade local in my area. I would say about just less then half my shots were good and usable. The day was overcast but i was still able to attain fast shutter speeds and low ISO using a 2.0 or 2.5 aperture for the day.
Summary: Not much else I can say that others haven't, it's a fantastic lens. Not a negative point about it, but something to keep in mind is that 135mm isn't at all wide-angle. You really need to be prepared to move back physically to get the desired shot.
Summary: Hands down, my favorite lens! It is simply amazing, and I love the images on both the A99 and A77. This is my go-to lens for portraits, low-light settings, and action shots. Bokeh is outstanding. Also have the 85mm Zeiss, and the 135mm is by far superior. Brighter colors, crisper, sharper, than anything else I've seen for Sony. Generally regarded as the best lens that Sony makes, and I totally agree.