I try to give star ratings according to the genre, the context of the time it was made, and the subject matter being tackled.
A movie tackling really big themes and making bold steps deserves a reprieve from a few blunders, whilst a formulaic comedy really needs some perfect footwork to be worth watching.
At the same time, some genres really can't get a whole lot better. No Blaxploitation can really be called cinema, but for their context in cinema history, are given fair ratings.
That said, the 4 and 5 star films manage to transcend their genres limitations (An action film with a good plot, a horror film with a good acting, a comedy with character development, etc.) 3 star films are average, they fall in line with their genres expectations, whilst 1 and 2 star movies might give you a pretty poor impression of the entire genre itself, and leave a bad taste in your mouth even for good movies of a similar theme. That isn't to say the movie itself is bad, it merely shows the rather seedy, unsuccessful side of a genre. Plan 9 From Outer Space is a film worth watching, but because it represents the same Sci-Fi genre as "Alien" or "The Day The Earth Stood Still." Poor films are necessary to appreciate the good ones.
Finally, entertainment value is something I really can't rate, but I'll note in a review. I really enjoy some pretty terrible movies, but I'll star them for how they are crafted and executed, and only rarely will I favor or deride a movie for its sheer entertainment value alone, or simply because I dislike it's content. When I do, it'll be obvious.
Herzog is an eccentric, and perhaps an acquired taste. This film hits you with the immediate bluntness and selfishness of a rookie documentarian, but an awareness that the man speaking from behind the camera might actually be someone worth listening to... not in a traditional documentarian sense of neutrality or cautious respect... but more akin to an entertaining and slightly absent-minded uncle waxing poetic and seeming a bit ridiculous, but still holding the room at rapt attention.
Encounters at the End of the World simply follows that eccentric uncle as he wanders around base-camp, talking about whatever wanders into our out of his mind, making unabashedly random and whimsical commentaries with glacial surety. It drags on, but Herzog is simply too forceful to let you go, and you end with a feeling that you were forced along for the ride but weirdly don't regret the experience.
Hero-worship is all too common, and this film sadly overindulges to the point of making an otherwise worthy subject instead a 2-Dimensional poster-boy for politically-correct heroism. However praiseworthy Desmond Doss's story, convictions, and actions may have been, the documentary does little to explore any emotion other than diamond-in-the-rough praise, with a requisite prelude of ingratitude and hardship. In the end, little is explored beyond a simple narrative that reads a bit too much like a propaganda film or comic-book reimagining (indeed, the film-maker cites his boyhood facination with a comic-book about Doss.) Doss himself is a bit too vague to provide much insight beyond that of a strange form of directors-commentary... and we are left with a sadly isolated view of an otherwise remarkable story, unable to connect any strings or make any inferences other than a big, blaring neon light leading down a path to hero-worship with as much substance as a Hollywood script-writer could manufacture in a weekend. Truly, the substance must have been there... but its direction and cinematic narrative structure have far too many stars in their eyes to unearth more than a few heartstrings to tug at.
A satisfyingly balanced, and for that all the more scathing, look into a rather minor but vocal sideshow of the American Heartland.
It feels like one of those micro-history books sitting in your local bookstore: focused on one subject and rarely if ever deviating to even briefly take a larger overview of its context, yet managing a true documentary level of implied social commentary, leaving the subject matter to work for itself. In that way, we can excuse this film for not tackling larger matters, such as Christian Fundamentalism as a whole, simply because Fred Phelps world is inherently isolationist and not open to these larger issues. The audience is left to interpret the morals and the role this group may have in the world at large, and for that, the film deserves a bit of praise considering the volatile subject matter that could easily have turned into a aimless hack-job. Instead, the documentary presents you with the axe, the grinder, and the instructions... and lets you handle the rest once the film is over. For that, its focus and lack of context is not misplaced: it knows the audience comes in with a preconception, and instead gives ammunition in the form of details, facts, and calm analysis. Satisfaction, and a fair bit of outrage, guaranteed... as long as one reads between the lines and doesn't make this narrow molehill of a subject into a broad mountain of disgust.