I have seen the latest 2 movies, and a long long time ago I did see the David Lynch version.

Overall I would say the book is great so far, though I am only about halfway through the first movie's plot. Probably the most significant difference that I'm enjoying is the added nuance to characters' internal motivations and thoughts, which generally are not present in the movies at all. Similarly, for some more specific details about how things (objects, scenery, atmosphere of a scene) are described, it may not be present in the movies - or even if they are there, in visual form they may not have attention called to them necessarily and/or a viewer may not notice them.