Using 'word for word' indicates a lack of originality or creativity since it's an exact copy. The actor's impression was good, but he mimicked the comedian's routine word for word.
Pro Tip 2/3
Memory Demonstration
This phrase can suggest someone has a strong memory if they reproduce something word for word. He recalled their conversation word for word because he remembered every detail.
Pro Tip 3/3
Accuracy Importance
'Word for word' use implies that getting the details right is very important. She needed to get the legal terms right, so she quoted the contract word for word.