Honestly, this was a bad movie. I went to see it with some friends who seemed to love it, but I could not get into it. I'm not a horror movie person, but it is not even the horror that made this a bad movie for me. It is the fact that the plot of this movie made absolutely no sense. For the first act, it seemed like a period piece that would discuss themes of racism, religion, and escaping one's past. However, this quickly devolved. It seems that as soon as the first vampires appeared, the director forgot that he was shooting a movie set in the 1930s and it became a vampire horror movie and eventually an action movie??? We went from scenes of a plantation and portraying life in 1930s America to Micheal B Jordan machine gunning down fifty people in the last scene. Not to mention that, at one point, the vampires all join together to do an Irish jig for the main characters which provides (unwelcome) comedic relief.
As others have mentioned, the writing is also sloppy and the writers introduce so many random plot points that seem to serve no purpose. Hailee Steinfeld's character's mom died the day before the movie is set?? This is just repeated multiple times as a fact rather than a plot point. Also, the vampires can now read each others' memories?? And instead of attacking, they stop to explain how they got there and what their motivation is??
Also at one point, there is a character twerking in the middle of this 1930s blues dance floor because the guitarist main character has summoned the "future of music"?? Along with 90s hip hop dancers and a DJ? I understand that this was trying to portray the evolution of African American music and culture, however this was such a random way to do it. This plot point could have been revisited and I think this vein of magic could have been explored to create a story where they fight the devil with music instead of a vampire story.
Finally, the last teaser scene half-way through the credits was so random and did nothing for the plot. Honestly, it left me more confused than if it had not been there.
Overall, I think this would have worked better as a period piece, with some magical realism rather than a vampire story turned action movie. I think that the movie lost the theme partway through and was building up to a good thesis for the first 45 minutes, but it quickly fell apart.