It's best illustrated by his scene-for-scene remake of King Kong.
The original had King Kong's fight with the T-Rex last about two minutes. That's maybe a little short for an action sequence, but it got the point and ended.
Peter Jackson had it last 11 minutes. It seemed like it would never end, it lasted so long you wished you hadn't watched the movie.
Lord of the Rings is a lot like that. In that all of the boring stuff lasts three or four times too long. We don't need fifteen minutes of Frodo and Sam staring longingly at each other.
Edit- The books... well, let's just say that Tolkein was a lot like Harry Turtledove. Great ideas for his stories, but simply doesn't have the ability to tell them in an interesting way.
[Edited by Dhampy, 1/18/2010 8:22:37 PM]