It is very soft at maximum opening, which when closed improves, as is natural, and its resistance to reflections is quite bad.
It is excellently built, everything works with great precision and without gaps and gives a very retro "retro" touch to photographs when used at full aperture. To avoid loss of contrast, care must be taken that the sun does not shine laterally, using an appropriate sunshade.
Overall this is a great lens for the price I don't regret the $60 I paid for it. Its also great for lomo and BW photography. I had to try very had to get lens flairs even facing the sun. I was surprised by the colors this lens produces, they are vibrant. I was also able to get some pleasing bokeh out of this lens as it picks up highlights in the background nicely.