The Tree of Life, to me, comes off as two completely separate movies blended together: a sweet coming of age story and a National Geographic-esque documentary about the origins of life. Does that sound like a big 'ole mess to you? Because it is.
The coming of age story is quite strong, if not completely realized. You follow the life of this boy, his struggles with his strict father, his relationship with his younger brother, and, decades later, how he is unhappy with his life. The problem is that decades-long jump. Why is he unhappy? How did he get to where he is? Did he make a wrong choice along the way that we didn't see? All these questions could be answered if there was any development at all with the older version - instead, Sean Penn mopes around his completely kick-ass office building, culminating in a strange existential vision where all his family members are around him. Does he miss his family? Is that the point? I suppose that makes sense... but it's just not clear.
Then we have the NatGeo segment. I had no flipping idea what was going on. First there's galaxy images then there's lava then there's dinosaurs then there's an astroid. How is this at all relevant to the other story? I'm sure you can make some artsy connection that merely connects them, but it most certainly does not enhance the main story. It all comes off as trying way too hard to be important.
Am I missing the point of this film? Quite likely. I hope so. I hate for a movie to be a completely disjointed mess that comes off as obnoxiously self-important and artsy.