Good:
-Violence and gore in this film are absolutely exceptional. In quantity and quality. A lot of memorable scenes for cruelty and originality
-Disgusting, disturbing, very very offensive but extremely amusing
-No CGI but good old special effects, with props, makeup, and a lot of fake (?) blood
-A collection of really evil nazi puppets that do the worst things to people who do not deserve it (which is the essence of the horror genre)
-A lot of black humour
-Interesting characters in their own oddity. Not only the main characters but even casual victims of the killing have characteristic traits that makes them unique (a line they say, a physical feature etc)
-Opening titles (the comic style is great)

Bad:
-There is more plot in the opening titles than in the entire movie.
The story is very simple, this can be a good thing because it allows the movie to be focused on the killings, but a bit more development would have added suspance and depth to the movie.
-Open ending (and we don't know when and if they will make a sequel)

If you liked the violence in this movie i recommend checking out S. Craig Zahler filmography. Bone Tomhawk, Brawl in Cell Block 99, Dragged Actoss Concrete are great movies.

DVD quote:
"Cuddly Bear don't wanna hurt nobody, even a hater, but Mrs. Cuddly Bear wants herself a new hi-def TV.
Cuddly Bear's got principles, but he also got priorities."