Thoughts on The Dark Tower books. (Just finished them)

I started reading The Dark Tower books about a month and a half ago. I was afraid to go into this long series at first, but once I started I couldn't start. The story was of course amazing, but that wasn't the most important part. The most important part of a book series is the characters. I loved Roland and his ka-tet, and,SPOILER ALERT, when a member died I almost cried, got pretty close to tears when Oy had to go. I love how the story basically ends how it began. My favorite book in this series is Wizard and Glass. What are your thoughts on King's magnum opus.