Very experimental for the time and it appears very much in the lineage of surrealist, abstract experimental films such as Un Chien Andalou, however, in this case the film is far more narrative and linear than un chien andalou and does not jump as much in time and space. The story itself is also centered around a central character, the woman with a distinct character arc that you follow.
It's incredible that this film was made by Americans. You'd imagine that this sort of experimentation would have been done by the Spanish, French, or German filmmakers of the day not the more traditionalist Americans. In a way this movie is the first INCEPTION, a Dream within a dream within a dream.
The film shows the threshold that filmmakers are at in terms of the angles they use and the camera work breaking the more traditional notions of close up, medium, and wide to now using canted angles, overhead angles, shooting through spaces and objects. The shot choices and psychological effect of the photography is very similar to Citizen Kane in putting you into the psychological mindset of the character rather than choosing an angle to best demonstrate what's happening in the story.
The WW2 period ushers in realism and psychological realism into film whereas the 30’s was defined by literality, extravagance and genre. America is starting to borrow realism and experimental techniques towards finding truth through the medium of film from Europe, which is being ravaged by the War.