I'm reading it atm and have mixed feelings. Sometimes, it seems like a silly kid's book, written by an overgrown Edwardian schoolboy. Then there will be a beautiful sentence, or a profound observation, or a snatch of poetic prose, and I begin to think it's an epic masterpiece.
I'm also re-reading Harold Bloom's 'Western Canon,' in which he lists what he considers the true canon of 'great books'. He lists most of the stuff you'd expect (Pride and Prejudice, Middlemarch, Wuthering Heights, Great Expectations, Jude the Obscure, Sons and Lovers, To the Lighthouse, etc), but not Tolkien.
I doubt you'll ever see it taught as part of a literature degree either. You might have it on the 'fantasy' module, or something like that, but nowhere else. Should it be taught alongside other major 20th-century novels? I'm thinking of stuff like Ulysses, Heart of Darkness, Atonement, and so on. I'm not making a case one way or the other. I'm just curious to hear what others think. Is it serious, great literature? Or just very good escapist fantasy?