What's the consensus on the books? I heard they're a mixed bag.
Mixed bag is the only way to describe them. The books are… uneven.
Good in spots, great in others, creative, good unique characters, and tie together everything King has ever written, and rightly credited as his opus buuuut... there are also long slow parts, the genres change drastically, there are extended flashbacks that take an entire novel that probably should have been told first, and worst of all...
The book were written over the course of 30 years and the fact that King had zero master plan shows. He had to rewrite chunks of the first book later on to fit the later books, the points where he hits writers block are super obvious, and the events of the later books were just... clearly not in any sort of early plan.
There are events later on that just completely break the series for me and make it flat out stupid and I would have given up on the series entirely at that point if I hadn't already invested years into it.
And the ending is awful. Not just the last couple page which is what people gripe about, but the entire last two books. Lots of let downs and deus ex machinas.
If you're already a King fan, and will appreciate how it ties everything together, go for it. If you're not... eh.
The movie looks like its going to condense a lot and cut out a bunch of the BS, so it might actually be stronger for it.