Many of us love Supernatural on the CW, and one just finished reading a tie-in book War of the Sons by Rebecca Dessertine & David Reed. She reports she enjoyed the story and the characters, but almost threw the book across the room a few times because it was so full of dumb mistakes that could easily have been corrected by a good editor.
The angel Abbadon sends Sam and Dean back to 1954 so they can acquire some Dead Sea Scrolls from an auction at the Waldorf Astoria Hotel in New York City. This gives the authors a chance to contrast life in the 1950's with the Winchesters' life today. But they get a lot of it wrong, and it is grating. In the most egregious (and easy to have checked) example, Don sent some other things back as well because a character draws the Arch to tell Dean she's going to St. Louis. But construction of the Arch started in 1963 (one of our member saw the photos her cousin took as it was built). We just checked her memory on Wikipedia, so the authors or editor could have done it as easily as we did. There are other painful errors that anyone who had stayed in a big fancy hotel in the 1950's would recognize (no ice machines then, or vending machines either. You want food or ice, call room service.)
Clearly the book was written by young people for other young people, and the publishers didn't believe it was worth investing in fact checkers for a genre book like this. But we suggest they have one of their older editors read such things in the future because it would have saved them a lot of embarrassment. The Arch error is ridiculous.
So the geezer in our group have now finished grousing about the stuff that drove her nuts, and calmed down enough to say what she enjoyed. She liked the premise that a demon was trapped in the jars to protect the scrolls. She liked the characters, especially semi-clueless Walter and his daughter, Julia. And the demon-wife of Lucifer, Eisheth. Walter's plan to stop the Apocalypse was definitely in line with Spock's "The needs of the many outweigh the needs of the few," but not with the Winchesters' "you don't kill fellow humans" philosophy. How Sam and Dean foiled it was clever and the ending was really satisfying. It fit right in Season 5, when the Winchesters were doing everything they could to avoid being Michael's or Lucifer's vessels.
So after all the discussion, the opinion was it was a pretty good book that could have been a lot better if a little more care had been taken with it.