Pentax's new K-1 Mark II arrives some two years after the original K-1 -- that seems to be the general update cycle for all but the entry-level models -- with only two real enhancements. Even those are made possible by a single hardware change. But these updates may possibly mean a big improvement for people who need better low-light quality or who use Pentax's Pixel Shift Resolution mode. Otherwise, it's identical to its predecessor in all ways but the name badge.
There are only two updates to Pentax's flagship DSLR, but they're potentially impressive.