I have read it. Proposes a wild theory, then next chapter presents that theory as fact and accumlatvely keeps doing it.
Glen is probably not being over harsh.... that said, it is often discussed (as is The Brotherhood by Stephen Knight, which is probably worse than the Hiram Key because Knight attacks us and infers and accuses dishonesty without hard evidence .... his accusations, and others like his, caused a real stink in the UK and unjustly affected careers... without the accusations surviving proper investigation ). It's worth reading both but out of principle I would not give Knight a dime...i got mine in the $2 shop where both books belong, but at least the Hiram Key was interesting, albeit fanciful.