I've heard some pretty negative things about the author William wolf, mainly centering on his U.S. Aerial armaments series of books, lots of things about sloppy editing and referencing , pictures not matching up with descriptions, and the author not taking criticism and negative feedback on his works very well. He has done ALOT of books on subjects I find interesting but I haven't gotten any of his works due to some if he negative feedback.
All of his works have gotten 4-5 Star reviews on Amazon though, which I find kind of surprising.