Earned it's place in history.
As a film this adaptation is a little clunky and a lot of bits feel very quickly pushed forward. It's also annoying that it's unfinished although that was hardly the intention bur regardless it's truly become iconic in it's own way.
As a first attempt to bring Tolkien's book to life it's very bold and done quite well given the limitations of the time. I was never that keen on the rotoscoping but now It's one of the film's most noticeable features and certainly gives the film an eerie, other worldly feel that transcends the safety of the animation. In other words it scared the crap out of me as a kid.
You can tell that Peter Jackson took heavy influence from the film in the way some shots are set up in his trilogy as he probably knew that this would have been a lot of people's first introduction to the world of Tolkien and the familiarity in the visual setups would be a great mental stimuli.
It's rough and not perfect but it's also fascinating to see such an early attempt at bringing the book to the screen and I think if treated purely as a piece of art and not film making it's truly a unique piece of work.