Here is the description of Box from the book:
"A creature stood before them on chromed legs. From the midpoint of his sternum to his hips he was coils and cables. One hand was a cutting tool. His head was half flesh, half metal."Terrifying, right?
Here's box from the movie:
But even worse is seeing him in motion. Box is the last obstacle the heroes encounter before escaping to the outside world. He's meant to be a terrifying threat (as insane robots are wont to be), but his slow, wobbly movements suggest that Logan and Jessica could simply walk briskly away to safety:
I understand the difficulties of bringing such creations to the screen, especially pre-CGI. But robots had appeared in movies for decades prior to this that not only looked more realistic, but had the ability to - I don't know - walk upstairs if they were so inclined. Instead they went with something built like a giant bottle of Mrs. Butterworth.