Oscar truly acts his ass off in this film. Mikael's arc from idealistic medical student going to the "big city," gradually transforming into a traumatized survivor of genocide who loses almost everyone he loves... Oof y'all. My boy's got range.
The rest of The Promise was a bit hit or miss, but it mostly hit. In particular, I was surprised by how much the love triangle didn't bother me; the film certainly didn't need it, but it navigated a simultaneous portrayal of romance and historical trauma better than most other films that try to use a love story as our entry point into a historical event. (It came off better than, for example, Oscar's love story in Operation Finale, which was distracting and boring.)
Also, the film's entire budget was donated by an Armenian-American named Kirk Kerkorian, which was the bulk of the reason that The Promise even got made. You go, Kerkorian.