I think aspects of psychology have real value, but there also seems to be a lot of weird and nonsensical junk mixed in. Anyone who's ever studied Freud (or Jung) ought to have at least some sense of this. MBTI, too, has its critics, and though I strongly identify with the NF temperament, I don't think I really buy the whole kit n' caboodle. MBTI doesn't fit very well with my own experience. Including its function-order scheme. I think I use Ni, Ne, Fi, Fe quite a lot. I can't just pick two and make the other two "shadow functions." There are way too many loose ends.
Here are a couple of interesting articles that explore this a bit more:
http://www.theguardian.com/science/brain-flapping/2013/mar/19/myers-briggs-test-unscientific
https://www.psychologytoday.com/blog/give-and-take/201309/goodbye-mbti-the-fad-won-t-die
That second article talks about some personality research that really does appear sound, but doesn't go as far into it as I would like. I'm looking into Keirsey's system more. I read somewhere, maybe on this site, that he kind of broke with Jung's wacky ideas and formed a more solid system of his own. From what I understand, it's both more traditional and better grounded in fact.