I don't think I've posted this here before, so:
Avoid books published by #Packt. They are an untrustworthy publisher.
Several years ago, they e-mailed me to ask me to do a technical review of a Hyper-V book. I know nothing about Hyper-V whatsoever. The offered compensation was "two books from their technical library".
Most likely they scatter-mailed anyone their Github scraper turned up, hoping that someone would agree to review. Because I *did* have a HyperVM-related repository, which is completely unrelated to Hyper-V, but would definitely match a 'hyperv' string match.
Even leaving aside the shitty ethics of not paying their reviewers properly, this also means that the average Reddit/HN-posted blogpost will have had more actual technical review than a Packt book. 
@joepie91 My deal was slightly better, THREE books from their library; don’t even remember the subject matter anymore. I wrote a 500 word reply saying hell no and never heard anything.
@joepie91 I got some of their books from Humble Bundle and to be honest, even if they weren't unethical, the quality is extremely hit and miss. Some were OK, some pretty bad.
@shine An unsurprising result, with that sort of technical review :p
@joepie91 oi, you just hit me with a tinge of nostalgia thinking about hypervm...