First, to the commenters (who obviously aren't reading this...): have some respect. Christopher Tolkien was extremely close to his father and made maps, advised, and acted as his copyist for years. The man knows what he's talking about. He's the next-best thing to having Tolkien himself available for criticism. (Tolkien père would probably have been much more communicative and explanatory, but that's beside the point.) And Christopher Tolkien is eighty-seven years old. You can't expect him to be either active in the LOTR phenomenon or accepting of changes to his father's beloved work.
At any rate, in principle I agree with Christopher Tolkien. There is a great "chasm between the beauty and seriousness of the work, and what it has become." The changes and many of the choices made by Peter Jackson do make a Tolkien purist, or anyone who understands his vision of his works, cringe.
However. First of all, one cannot expect perfection, least of all from Hollywood. Also, there is a huge gap between the culture of the era in which the books were written (and hence Christopher Tolkien's era) and modern culture of the era in which the films are made. I think it would probably be literally impossible to make a film that grasped Tolkien's ideas, was accurate as to characterization and events, was stylistically accurate, and didn't leave anything out. Peter Jackson is guilty on multiple counts, but he did get some things right - sometimes amazingly right. Considering what he was up against, he did a fairly good job. Sometimes. Agh, I don't know. It is very confusing. And I actually haven't even seen The Return of the King. Anyway, what I wanted to say is that the films, in and of themselves, are gorgeous, glorious works of fantasy. It's just when you compare them to the books that you run into issues. But of course, every bookworm knows the maxim that the book is always better than the movie.
(Note: now I feel a slight bit guilty for my positive-ish review of The Hobbit.)
So yes, Christopher Tolkien is right in condemning the film franchise's deviations, but I think that if you realize that the films are flawed (and make sure you don't get too wrapped up in them), you're fine.
Just in case anyone was wondering, yes, I have had a slight (oh, very slight) relapse into active Tolkien fangirling. It has to do with reading The Silmarillion and seeing a certain independent film which I shall post about another time.
So, comment and give me your opinion on the LOTR books-vs-movies debate. I love to discuss these things and hear others' opinions.