Summary: I love love love this lens! I was impressed when I opened the box by the quality compared to the kit lens. Amazing image quality. I can definitely tell the difference! I couldn't be more thrilled, so I purchased the 18-50mm model as well. They are both great lenses at great prices. Needless to say, I will be sticking to using Sigma lenses for my personal and professional photography needs from here on out.
Summary: I absolutely love this lens and love the picture quality. I use it with my Nikon D5100 and haven't had any problems. My only complaint is that if the lens "thinks" I'm too close to an object, it won't focus or take the picture. Other than that, I haven't had any issues with it.
Summary: I found that i spend way more time at 200mm than i do at any other focal length mostly because the bokeh is amazing. Very little lens correction needed in post. I love everything about this lens great work from 50 to 200 The weight is great the markings for the focus point are extremely accurate, the auto-focus works pretty quick and very accurate.