Song to song is an exploration of love and ambition set against the Austin music scene. Especially around the theme of love the movie makes interesting observations: That true love is only possible by isolating yourself from the fake world (of music and money here), that walls are built around you inhibiting you from finding real love. Another observation is that early in life you love everyone, but ultimately your awareness, society, and religion lets you end up with one true love, unable to love others any more.
The notion Malick makes about love is the romantic character of love itself, romantic not in the sense we nowadays attach to it, but the original meaning as an unattainable ideal, combined with adoration of nature and emphasis on the individual and its intense emotions, the latter creating beauty and experience. Romanticism was mainly a reaction to industrialization and urban sprawl: All Malick movies have shots of urban landscapes and nature scenes; they look for beauty in that nature and have a preference for searching for intuition instead of filming fixed storyboards.
The story however develops in a non-romantic direction: Where in the quintessential novel of the romantic (or more precisely Sturm und Drang) movement the main male character shoots himself after being rejected by the woman he loves (Goethe's Die Leiden des jungen Werthers), Malick replaces that hopelessness with a man who commits adultery, has regrets and is punished and tested by the woman he loves who commits far more and extremer adulterous acts.
Malick uses again a naturalistic style of filming, adding unscripted moments that occur during the movie shoot. Some footage is shot at the Austin City Limits festival and short interviews with John Lydon and Iggy Pop are included. The state of Texas features prominently: a key scene is before a Texaco gas station for example, but overall it is the unusual, non-clichéd beauty of both nature and the built-up Texan landscape that is well captured by Lubezki's camera, making effective use of wide camera angles. It also feels less slow and has more snappy cuts than Knight of Cups, which will be a relief for many I guess. The editing by a team of 8 (!) editors is however inconsistent and one of the weaknesses of the movie.
Two actresses in the movie have in my opinion the capability to give this an extra level, to give it real character depth acting on multiple levels in order to convey the emotions Malick's movies are oddly enough often lacking despite aiming for them: Portman and Blanchett. They are so underused and reduced to cardboard characters that it can almost be called a shame.
What struck me also about this movie is how conservative and deeply religious Malick's world view is: He clearly roots for Patti Smith's love story she tells in the movie for example, and sees the other musicians and portrays them as lost souls. In Song to song the woman repents, but the man only regrets. I see a parallel here with Tarkovsky's movies, which show the same religious, conservative world view. It brings up an odd observation: These two movie geniuses shatter the notion that true art can nowadays only be made by free souls, their art more in line with church-supported art like it used to be (Note: See The Tree of Life explanation by Bishop Barron).
Von Trier once remarked that he in effect makes the same movie over and over again, and Malick has come to that same point now. He has perfected his storytelling skills, hides the movie in the images and by editing, uses time and space shifting, sees salvation in nature (the element of water is effectively used here), adds autobiographical elements (music, adultery, suicide, father-son relation, ambition), so Radegund can hopefully be the creative destruction many now hope for.