Tolkien on Film is a collection of essays on the Peter Jackson films by Tolkien experts. They're not all throwing out the welcome mat for the trilogy (one essay very amusingly states that Jackson has a nine-year old's understanding of LOTR), but the essays cover a great scope of opinions on the films and changes made for adaptation's sake.
If you are a fan of the movies that believe they possess no flaws, Peter Jackson can do no wrong and/or that Jackson told the story of the Ring better than those smelly old books by Tolkien, this isn't the book for you. You won't get far before you're throwing it away from you in disgust. But it does really depend on the reader as how they view the films and criticism of the films to how they receive the book.
Personally, I found all but a couple of essays very interesting, even if I didn't entirely agree with some of the arguments made or the opinions expressed. Some were even quite entertaining. I also enjoyed that neither one of the two essays on Tolkien fanfiction never explored the question of fandom and fanfiction in negative terms. I very much hope that there will be a second volume, focusing on Jackson's Hobbit trilogy.