I have all the companions and enjoy the shows. This does add to the enjoyment but has obviously got a fair bit of padding. For me the most interesting parts are the interviews with cast, crew and writers and analysis of the story arc. However the majority of the book are epsiode guides which to be honest could easily be found on the internet. It's not a must buy but reading having seen the series does add something to re-watching and indeed makes you want to watch again.