Processing:
Solid. There is nothing to complain about. Yes, it is indeed plastic, but by no means cheap effect. The switch for the Stabislisator and focus are constructed such as. At the 70-200L lenses. A lens hood is NOT included (with Canon you can;)).
Feel and weight:
In terms of size, the lens is already massive. Therefore, the low weight all the more surprising. The focus ring is a little stiff and not grippy enough that one could focus with just one finger. From the minimum focusing distance to infinity you need a rotation of about 160 °. The switches are well errichbar and can be problematic switch (no terminals and no slipping).
Image quality and Autofkokus:
The lens is sharp from open aperture, the bokeh is pretty soft with very round lights, contrasts are well reproduced. With respect to these points mentioned it delivers subjectively considered the same performance as the 85mm 1.8 USM, which I also own. In many other reports we read of violent light falloff at the edges (vignetting). Which is probably related to the full format. On my Cropsensor I can also notice a light falloff at full aperture, however, is the very most noticeable when you shoot a white wall or a bright sky. Stopped down to 2.8 has disappeared vignetting. Chromatic aberrations there are not, at least I did not have to discover. Conclusion of this: without limitations from open aperture -> vignetting can nowadays yes let out count of various programs.
The autofocus is really very fast / accurate and audible. You can hear a slight grinding, which would appear to lower the speed, than it actually is. Audible is in but only that one hears him when everything else is quiet. The stabilizer is it silently (clack other lenses and whir as partial). Exposures of 1/3 second from the hand are possible.
Bottom line, the lens is a worthwhile investment. The picture quality is great, the autofocus is fast and accurate and the stabilizer works fine. Still, I wonder why the price is so high. By comparison, the aforementioned 85mm 1.8 will cost around 350, the 35mm 2.0, however around 500 upwards. Apart from the image stabilizer and the different focal length, the lens differ virtually not at all. So I think that the price is (still) too high for this lens.
As alternatives, there are the more expensive Sigma 35mm 1.4, the cheaper Sigma 30mm 1.4 or viiiel expensive 35mm 1.4L Canon. Who uses full-frame, 30mm must even emphasize. They all have a larger maximum aperture, but no stabilizer. What is an important, you have to make course with itself.