It was a toss up for me between liking both equally and loving the books but enjoying the movies a little less. I finally chose that I like them both equally - but I have to say that though I really like BOTH, its most definitely in a different way.
Movies and writing are after all are both different art forms and tell a story in a unique way that though reflects the other, it can't be exactly the same.
Despite the fact that I will always be more devoted to the books than anything else, I really do enjoy the movies for what they are. I think that the movies can bring a depth and perspective to the story that wasn't there before. In the same way, I feel as though the books are the ultimate authority on the story.
You see, I grew up on both the books, the BBC movies and animated Narnia. So for me, that gave me the fullness of my imagination as a child, and so I look forward to seeing the different additions in the movies because to me it adds dimension to a well loved story that I've read or watched a million times.
As a result, there are moments when asked about a specific scene, I will sometimes describe the scene as it were in BBC Narnia - I don't mean to, I do know better, but because this is what shaped my imagination as a child, and so has set the picture of my Narnia now in the present.
At the same time, I do have expectations that the movie merely enhance the wonder and magic and plotline that is already there. Believe me, if they, for example, took the Eustace Dragon out of Dawn Treader, or had Caspian come to England at the end of Prince Caspian...or have the Green Witch turn said Eustace into the dragon...I might have a little steam coming out of my ears, but for the minor changes and additions it simply enhances my Narnia experience.
In some ways though I really think that this is entirely in line with Lewis' instructions to his young writer fans. He had full expectations that we would imagine stories in Narnia on our own and write it down. He invited us to share in the creation of Narnian adventures...and so we have. This, I think is why we have so many different varying viewpoints of Narnia - because we all have imagined Narnia on our own, which is exactly the gift that Lewis gave us.