Without spoiling the ending, it just felt as if the two main characters, Mildred (McDormand) and Rockwell (Dixon), go in a direction that is so inconsistent with their characters moral arc that I found it jarringly unbelievable.
Also, the lack of resolution alone didn't bother me--I can deal with that because it's real and how life actually usually is. But it was frustrating BECAUSE of the sudden, jarring change in character development.
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It really didn't work for me that Dixon seemed to be redeeming himself and then he and Mildred go plan to kill someone that probably deserved it, but was absolutely NOT connected to the rape and death of Mildred's daughter. For similar reasons, I found it inconsistent that Mildred would suddenly become a vigilante a la Paul Kersey (Bronson) in "Death Wish."
Previously, her anger was justifiably directed at the unknown person that killed her daughter and then understandably projected it on the Police Department for failing to identify a suspect, let alone bring one to justice.
When she was verbally assaulted in her store (by the creep that Dixon later mistakenly thought to be the perp) she basically just stood there and took it in silent rage. For her to later decide to go all "Death Wish" on the guy and become a vigilante seemed inconsistent with her character and not particularly believable or satisfying.
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