I've been hesitant to write this post. I don't really like writing about equipment, especially equipment that I don't own. However, people ask for these types of posts and they are always popular, so here I go.
DxOMark tested the Pentax K-3, and it scored really well, yet perhaps at the same time it was a bit disappointing. Pentax moved on from the Sony 16 megapixel sensor that they've been using for a while now, and with the K-3 began to use Sony's 24 megapixel sensor that is found in several Sony and Nikon models.
The K-3 scored really well, and it is one of the top DSLRs with an APS-C sized sensor. But I (and some others) expected it to be the top #1 DSLR with an APS-C sized sensor on DxOMark's list. That is because Pentax has a reputation of squeezing just slightly more out of the sensor than Sony or Nikon can. Instead, the K-3 fell right in the middle, just ahead of the Sony SLT A77 and just behind the D7100.
Does it matter if the K-3 isn't number one? No, not really. Is there a difference in image quality between the A77, D7100 and the K-3? No, nothing that is noticeable without close studies of test charts. So who cares? I don't. Besides, DxOMark scores don't mean a whole lot, anyway.
The fact is this: the Pentax K-3 is a fine camera, but it is no better or worse than similar cameras offered by the competition. If you are looking for a quality DSLR with an APS-C sized sensor, this might be the camera for you. And the Nikon D7100 might be the camera for you. And the Sony SLT A77 might be the camera for you.
If you are trying to decide, perhaps consider lens choices and prices and let that be your guide.
In any event, cameras are not important, photographic vision is. Creativity trumps equipment every time.