Doesn't look anything like what I read in the books. The impression I got from the trailer was that the film is a reinvented version of the books that's far less darker and shallower. King seems to think it's fantastic and that fans of the books will love it. I have my doubts.
I saw an article last year about this, and i believe King stated something along the lines of this being one of the many reincarnations of Roland and his quest. It's not supposed to be taken from the books exactly, but certain events play out similarly or have a connection somehow.
If King was involved, and gave his approval, I'm inclined to trust him on that.
It does look like the generic summer shoot em up blockbuster, though. So I'm not sure how I feel.