According to The Washington Post, Campbell's works are:
"Slightly above average"
"Innovative but flawed"
"Monumental accomplishments"
"Repetitive and dull"
Answer
The Washington Post regards Campbell's works as "monumental accomplishments." Campbell's contributions are deemed highly significant and substantial, leaving a lasting impact. His works are considered notable and remarkable achievements in their respective fields.
Mysteries of the Macabre: The Ramsey Campbell Challenge