Nice lens. It can focus hunt in low light due to minimum aperture. A little soft wide open but works great from f/8 to f/11. Nice and sharp. My go-to birding and wildlife lens, nice and solid. The new Tamron is intriguing, but I have no reason to want to get rid of the Sigma, particularly before seeing any real photos from it (there's just promo stuff). I've gotten great results with it on a D90, D7000, D600 and D800, so I'd imagine you'd be fine on the D5200.