The K50 uses the same sensor that's in K5 and Nikon D7000. It's a 16mp apsc Sony sensor :P
At the time of it's release it had the best dynamic ranger available. So maybe that's why I'm not impressed, because I've been using an old but great Sony sensor. And my camera has IBIS too :P
But it does show it's age. High ISO noise is pretty bad and the AF is from the stone age :D