So, first off, I'm going to say that I've only read TMN, TLTWTW, and PC. I've listened to the Focus on the Family Radio Theatres of them all, however, and as I understand they are very close to the books.
With that said, I want to say that my favorite book is the Silver Chair, followed by The Voyage of the Dawn Treader.
When TVDT movie came out, I was very excited. And as I watched it, I was still very excited. And at the end of it, I was very pleased, satisfied, and still excited. Honestly, I don't really get why people are upset that the filmmakers changed the story. When you go to a movie, do you really expect an unchanged story? Of course not! And the TVDT would have really made a looooong and boring movie. Just think about for a moment, will you? As much as I love this story, it really wouldn't have fit on the silver screen.
Now, I do think they could have lengthened the movie because they could have captured the length of the voyage better, but overall I think they did a splendid job. 
Yes, I am being the opposing one here who actually loves that movie. But before y'all all get fired up against me and get ready to throw me your reasoning on why you disliked it (and I say that teasingly 

 ), allow me to share with you my reasons for liking it.
I felt like TVDT captured the essence of the story. An adventurous sea voyage in a fantasy land. All the different lands they travel to. Yes, I realize they changed some of the lands, combined a couple, and rearranged some orders. But does that really matter? They still travel to all of the lands. And I actually liked how the combined Death Water Island with Dragon Island. A very fitting match if I do say so myself. 

"But the green mist was very lame. I mean, where did that even come from?!" you say? OK, so maybe that was a major change from the book, but I actually liked what they did with it and turned it into Dark Island. It was almost like the mist was the spirit of the White Witch, keeping her throughout the stories. That works, because in the Silver Chair the Lady in the Green Kirtle is basically a reincarnation of the White Witch. So it's just keeping that tie in there. It also gave the heroes more conflict. Instead of just the smaller conflicts at each island (which they kept), they also had an overarching evil that they had to deal with. This helped move the story along and keep it from becoming boring and pointless. Although I would have preferred it as the original tale, for the book on the screen, I felt like the staff took care of their problems very well.
"But with all of these changes, the intent of the book was lost! Especially with Eustace's transformation! They could have done so much more with that." True, I think they could have done more with that. But did you hear Eustace recap his experience? He described everything that the book described, just at a different timing. For the time restraints of the movie, they handled the dragon transformation excellently in my opinion. And you even got the gist of the original scene from the book. But I disagree that the intent of the book was lost.
I didn't like Prince Caspian as a book adaptation. I enjoy it as a movie (and the kiss did bother me at first, but it doesn't really bug me anymore... especially since they added the romance in there in the first place...). But I enjoy TVDT as a book adaptation as well as a movie. Why? Because I felt like they kept the essence that C.S. Lewis evoked in his books in the movie. In Prince Caspian, even though the order of events were more like the book, they lost what C.S. Lewis's essence that he had in the book. Especially with the characters. Susan's character was right, but I felt Edmund and Lucy were a bit off, but Peter the most. Even though they showed Peter's struggle, and I kind of like that, they did take it too far. In the book, Peter had no problem handing over the throne. He realized his time to rule was past, and he came to Narnia to help Caspian, not to become in charge himself. But that's just my opinion.
But it was kept Lewis' essence in TVDT. The adventure on the high-seas, the development of the characters, (yes, especially the development of the characters. They showed Edmund's struggle [similar to Peter's, but didn't take it too far], I loved the scene where Lucy said the beauty spell). I can't really describe it, but I felt like C.S. Lewis would have enjoyed the movie. Of course he would probably have his critiques, and I'm not at all saying the movie was perfect. There were things I would have changed, such as at least slowing the pacing down a little bit so we could savor each land a little bit more and capture even more of that lovely essence they evoked, and I didn't really like the dad and her daughter thing as much (though it was kind of nice). But overall I think they kept the spirit of the book in the movie fairly well.
So... there's my long rant. Sorry it's so long, and if it felt offensive in any way, I am deeply sorry. It wasn't meant to be so in any way, shape, or form. I'm just trying to show my side of how I view the movies and maybe help you see past the changes in the movie.
Oh yeah, and who didn't like that last scene in TVDT? I mean, that scene was caught perfectly. I loved how Caspian was tempted to go into Aslan's land, but then chose not to. And then Reep going over. Shawn cried in the theater at that part. 
 
 
 And then the children having to leave. 

 And Aslan was great, too.
And in case there's any confusion, this post does relate to the intent of the thread because it's relating the movies to the books. Otherwise I would have posted in the fireside thread on TVDT. This post was not meant to derail the thread.
Final thought on a book related note: I was surprised more people didn't pick The Silver Chair. This has been my favorite for a LONG time. I love the adventure and the general feel to it. It is a bit darker than some of the other books, which is probably why I like it. And Puddleglum is AMAZING. 
