If you're buying this lens, know that the autofocus system is extremely finicky and prone to malfunction. It's the biggest and most common problem with the lens. Other than that, the image quality is quite nice, especially for this price.
RashkhYes, I had one of these and it worked great for several years. I pulled it out of my bag at an event and autofocus was gone - but so was manual focus. After researching, I learned that any force applied to the front of the lens can distort the guide rails inside. I loved the image quality, but the cost of fixing it was too large a percentage of a new lens. I went with Sigma's older 50mm then and love it. I'm saving up for their Art lens now.