To me that wasn't all that bad. Just the anti-climatic final battle with the Crimson King (an underdeveloped villain to say the least) and the really flat deaths of the major villains (Mordred and RF)

With King there are no other long multi-book series' though. There's the Bill Hodges trilogy and The Shining got a sequel (Doctor Sleep) but other than that I wouldn't let the sub-par ending of The Dark Tower series affect how you read King's work.

11/22/63, Under the Dome and The Stand are three examples of King doing long novels really well. Loved all three. The adaptations of all three aren't particularly good though.

And yet book five marks the last true high point of the series. My opinion of course.

It was almost like the townspeople turn on Roland like a zombie-horde. King brining his signature horror element to The Dark Tower, as he did in many moments in the series.

One of the main issues is that The Dark Tower is a western mixed with a variety of genres (mostly fantasy and sci-fi) and this film has barely had any desert imagery promoted.

I think he'd be spot on. He'd play a different style Bob than we're used to, but Knepper brings his own brand of villainy!