Okay, so this is an attempt to answer your question of "What is it about Dylan?"
IT'S THE MUSIC...few artists have explored so many different types of music genres. He has mined the territories of bluegrass, folk, rock, country, gospel & blues. Dylan has taken an organic approach and never overmade music with machines or electronics. With one or two exceptions the production and engineering of his albums have been in the background.
IT'S THE MELODIES...like many coming from the folk tradition, he began his career by twisting and revising old folk tunes as Woody Gutherie had done. So many of this songs have beautiful, hummable melodies and tunes.
IT'S THE LYRICS...like all great poets, Dylan's use of words is mindblowing. For me, noone has ever quite expressed the range of emotions, thoughts and ideas as effectively as he. His use of imagery is amazing - check out the lyrics in "A Hard Rain..." Because he is identified with the 60's so many have tagged him a "protest singer" which ignores the majority of his work - and is way too confining. While his political and social songs are terrific, his greatest lyrics are about relationships and the human condition. His lyrical reach is much broader than his well-known early political songs. But even those songs are deeper than the causes that inspired them.
So many contemporary love songs are simplistic, his relationship songs are naked, honest and insightful. They are about the way people really feel and relate to one another, not sentimental hoo ha. They are romantic and touching, but operate on a higher and deeper plane.
Peter Paul & Mary's overblown verion of "Blowin' in the Wind" connected that song to the Vietnam War movement, but reading Dylan's words I draw a vastly different conclusion. His greatest political songs like "Masters of War" and "Hard Rain" are not pigeon holed in time, but are still relevant. So many of the popular political songs of the late 60's and 70's now feel so dated.
IT'S HARD...whether it be his voice or the dense lyrical content, Dylan takes effort to appreciate. Most pop or contemporary music is catchy and doesn't require much of the listener. In order to get Dylan - it requires effort. You need to listen, follow the words and think about it. Dylan is not for the casual.
IT'S THE ART...Dylan is really the individual who changed the perception of what rock and roll is. No longer was this music just adolescent child play, but art that had deeper meaning. I am able to find real truths in his art - the same way I find truths in the art of Mary Cassatt or Henri Matisse. One purpose of art is to help us analyze the world in which we live, Dylan does that for me. I am constantly discovering new meanings.
IT'S THE LIVE PERFORMANCES...Bob is a road warrior. Now in his late 50's, he has been on never ending tour for nearly a decade putting in over 100 shows around the world a year. In performance, he reworks his songs, changes instrumentation, melodies and pacing. He does some songs acoustically and others electric. Many performers do the same set night after night, Dylan changes the set - constantly surprising his audience with rarely performed songs. It's a drama that unfolds nightly as opposed to some slickly produced production. This all means there is some risk, catch a good night and catch a bad night.
Dylan hates the recording studio. At times he doesn't even share the songs or muci that he is about to record with the other musicians present. He will tell them just to watch him and play along. This can result in some less than successful studio recordings. It is often on the road that a song transforms and realizes itself.
IT'S THE LONG CAREER...He's been around for four decades so there's alot to cover. He became a born again, he went Las Vegas, he went electric; there's just alot of stuff to know. He's officially recorded 500 songs or so, had 40+ comercially released albums, wrote a book, wrote and directed a film, released a book of sketches that's a ton of material.
IT'S THE INFLUENCE HE'S HAD ON MUSIC...unquestionably one of the most influential artists of the 20th century. He's has influenced everyone that came after him from the Beatles on up.
IT'S THE FACT HE PISSES PEOPLE OFF...Noone has confounded his audience and the "critics" more than Dylan. he was the Leader of the folkies when he went electric (Pete Seeger attacked the stage with an axe to sever the electric lines), he did a country album in the late 60's that perplexed all those hippies, he became a Christian and did a trilogy of religious records (you can imagine how that was received). Not only does he follow his own muse, but does so while risking everything that came before it. He has always had the courage of his convictions to take a risk.
IT'S HIS VOICE...oh the voice. No artist has been vilified more for his voice which I find incredibly expressive. And his voice has constantly changed. Singing, of course, is more than just the sound you make, but the feelings and emotions you can express.
IT'S THE HARMONICA...his harp playing just sends me into orbit. It's such an honest and revealing instrument. He has played less in concert of late which has been my sole recent disappointment.
IT'S THE BOOTLEGS...there are over 600 illegal bootlegs of his work, he is the firs bootlegged artist. It consists of two basic areas: live concerts and unreleased studio recordings.
There is a large amount of unreleased material that his record company, has inexcusably not commercially released. Under pressure from the Dylan Nation, they have in recent years begun a process of getting some of that material out.
Dylan has toured with a number a different bands resulting in a different distinctive sound in various stages of his career. You gotta have it all. There is a tremendous Dylan culture and lure on all of this. They are books, websites etc. on all of this stuff, it's a world unto itself aside from the commercially available discs.
That's it, see if you can find it.