It's obvious to compare this film with "Baader Meinhof Complex", which deals with the years 1967 to 1977. The films overlap in the portrayal of the years 1967 to 1970, but they are very different. The films pursue different goals. "Baader Meinhof Complex" is a historical portrayal of the big decade of German terrorism. "If not us, who" is a love story, which attempts to show us the thoughts and motivations of the two main characters, why they loved one another and why they split up. While it's not as exciting as the other film, "If not us, who" succeeds in its goal. It puts us into the head of Gudrun Ensslin. In "Baader Meinhof Complex" she appears remote and psychopathic, but here we see her naive idealism and her genuine intentions of doing good, however many people she needed to kill to achieve her goals. Bernward Vesper isn't mentioned at all in "Baader Meinhof Complex", so it's fascinating to see this man who was a big part of Gudrun's life before she met Andreas Baader. He's a tragic character, torn between his hate for Fascism and his love for his Fascist father.
Andreas Baader is only a minor character in the film, even after he becomes Gudrun's lover. He's almost like a ghost floating through the scenes. We see him, but we don't know him. That isn't the film's intention. If we want to get to know Andreas and his motivation we have to watch the other film.
Overall, this isn't an easy film to watch. Only those who already have an interest in Gudrun Ensslin will enjoy it. That includes me.
P.S. In the final "what happened next" texts we read that Gudrun and Andreas committed suicide in 1977. There are no facts that support this theory. They were murdered.