Substance: The bulk of the book consists of encyclopedia-style (but not quite encyclopedic) entries about fictional amateur detectives, followed by some limp advice on how to write novels about the same. Laundry-list of classic and contemporary writers was stultifying rather than enlightening (and omitted Dick Francis and Tony Hillerman!).
Emphasized a focus on relationships rather than sophisticated plotting (which is why I find contemporary books generally poor mysteries). Quotes Good Housekeeping rather than any scientific sources, and perpetuates many outdated schticks. Best chapter: listed records that are accessible to public (although the actual law and IT are now out of date) and mentioned things you (the mystery writer) might not have thought of on your own.
Does mention one actual amateur detective who became a serial 'tec (Jim McClosky); however, most real "detectives" are only interested in solving their own real-life crime event (Susan Billing).

Style: Not the best. The authors are not themselves good writers, and the editors were abysmal. Poor syntax, poor paragraphing, and outright spelling errors abound.

NOTE: "The Fugitive" is a fictional version of the "real person" detective, solving other people's problems while trying to solve his own. ( )

I haven't gotten to this one yet, which is a shame. I need to write more cozies.