I really enjoyed reading The Time Traveler's Wife but the movie was a complete disaster. I had a sneaking suspicion that the book would not translate well onto film and I was so right. The script was awful and Eric Bana was horribly miscast as Henry. Rachel McAdams was perfectly cast as Clare, but for some unknown reason they died her hair the wrong color, and the horrible script was not something that could be overcome. This was probably the worst translation of a book into film that I've seen.
Every adaptation of Pride and Prejudice other than the BBC/A&E miniseries. Note to Kierra Knightly: Elizabeth Bennet does not giggle.
Don't Look Behind You by Lois Duncan. This book was adapted to a TV movie and it was truly awful.