The simple mythical story suits our times. The bad guys are ever so bad and the good guys are ever so good. Actually, "mythical" is the wrong word. True myth has nothing to do with good and evil. LOTR isn't a myth it's a morality play.
I don't think it's possible for a morality play to be great art- and LOTR certainly isn't, neither the book nor the film.
Tolkien stole Gollum from Dickens. He's part Fagin, part Uriah Heep.
God, but aren't the Riders of Rohan boring!
The scenes I like best in the book go for little in the film. The Mines of Moria and the Dead Marshes. Jackson's Dead Marshes are particularly feeble. He doesn't do spooky at all well.
Talking about spooky- the silliest thing in the story is the bit where Aragorn rides to the rescue at the head of an army of deaders. Tolkien rather skates over it (as well he might) but the film exposes the full absurdity of the idea. An army of monsters is swept away by an army of ghosts- all green and glowy like halloween novelties- oh please!
The battles scenes are OK, but they're not the greatest ever filmed.
The greatest battle scene ever filmed is in Orson Welles' Chimes at Midnight.
The second and third are the opening and closing sequences of Saving Private Ryan. The battles in Kurosawa's Ran are pretty amazing too.
So why didn't they just get one of those eagles to carry the ring-bearer? No-one ever sees them coming. Frodo could have dropped the ring into Mt Doom from a great height and- bingo- the whole mission would have been done and dusted in half an hour.