Very uneven. Extremely good stuff, along with pure cr*p. Much of it doesn't do well on the screen.
Have you ever read his "On Writing"? He admits to (even embraces) the title of "America's schlockmeister", acknowledging that he writes some of his stuff merely because it sells and he has bills to pay, and takes his time crafting more deliberate works that he feels are his serious literature, but knows will not sell as well.
I agree, his stuff generally doesn't translate well to film ("Stand By Me" and "Hearts In Atlantis" being two exceptions). I'd like to see the "Dark Tower" films do well, but I don't see it being done in three feature length films, and I don't think Ron Howard is the best choice of director for these. Roland Deschaines meets Sheriff Andy Taylor.
Yes, I would agree with that. I like the movies though, even the really bad ones. Comparing some of these older, campy king movies to modern horror (anything past 2000 really) shows that the king moives are substantially better. Good horror is very rare.