I almost didn't watch Song to Song last night. Terrence Malick's The Tree of Life is one of my top-10 films, but To the Wonder and Knight of Cups tested my patience too much between their moments of transcendence. The only thing I really remember from Knight of Cups is Natalie Portman's searing performance and that was about 10 minutes of the movie. I remember nothing from To the Wonder except a few images. (I enjoyed the IMAX Voyage of Time but in an entirely different way -- mostly because I could take my kids to a Terrence Malick film!). So, I had Song to Song from the library for two weeks and I almost didn't watch it.
I'm glad I did. Song to Song is not the masterpiece that The Tree of Life is, but it doesn't try to be. It has a strong enough plot and more importantly strong enough performances from all four leads to carry it through. There's enough similarities between the "post-Tree" films that To the Wonder and Knight of Cups seem like rough drafts, pointing toward Song to Song as the finished product.
The cameos from various musicians and the songs from all types of genres help color in the corners, too. The musicians are more real than the actors sometimes. The real center of the movie to me was Patti Smith, who tells her story of loss and sings a beautiful song about God.
Ultimately, this movie is a scattered journey through a moral universe. In fact, I feel like the morality is a little too open-and-shut, but I much prefer that to the wandering solipsism of Knight of Cups.