I don't remember when I last re-read THE LORD OF THE RINGS, but it's definitely been over twenty years. I've finished the first two volumes and have begun RETURN OF THE KING, but as I read the books, I find myself calling to mind my original reaction from the 1960s:
A lot of Tolkien's characters are BLOODY BORING!
The Oxford don does come up with a number of good touches for his main characters, and those touches are the reason why the book has remained popular these many decades. But a lot of his subordinate characters are dullards. Yes, Theoden and Denethor serve different plot-purposes, and enjoy different character-arcs-- but as characters, one is no more developed than the other. Many Tolkien-fans despite the film-adaptation by Peter Jackson, but at least I didn't have trouble distinguishing one king from the other.
I remember thinking back in the 1960s that this was the one thing that kept LORD OF THE RINGS from greatness: that so many of the characters were dull ciphers, no more alive than figures in a history-book. I wished that someday someone--maybe even me-- might write an epic fantasy in which even the subordinate characters were intensely alive, were individuals as developed as fictional characters can be.
And yet, on some occasions, I've seen Tolkien attacked for his lackluster characters-- and I usually find myself coming to his defense, possibly because there is a special art to fantasy-characterization that isn't identical with the world of "realistic literature."