I think the film was actually well constructed keeping the fact in mind that throughout the entire infinity saga, black widow's back story was never really told clearly (a brief in Age of Ultron). So in the stand alone movie where you need to develop the past and also need to put exciting unprecedented acts and action, i think it was well tried. As a genre of fiction the story was acceptable but what not acceptable from THE MARVEL STUDIOS was the cheap editing and VFX and green screen works in certain action scenes. That's the only thing that made me feel uneasy, specially after watching so many technically well accomplished marvel films.