A text classification system is designed to identify content expressing adverse emotions or attitudes, such as frustration, disappointment, or criticism. Read the following product review and explain why it would be categorized as 'Negative', referencing specific phrases from the text to support your reasoning.

Review: "The setup process took much longer than advertised, and the user manual was not helpful at all. While the device does eventually work, getting it to that point was a real headache."