Much has already been written about this controversial masterwork, and an immense amount more will certainly be written. It is undoubtedly deeply autobiographical. We know little of the reclusive Malick himself, but he grew up in the town where the film is set (Waco, Texas), and his own brother committed suicide at the same age as the brother in the film at his death. Critics who knew small-town Texas in the 1950s say that its portrayal in The Tree of Life is uncannily accurate. I would hazard a guess that the parents in the film are based closely on Malick's own parents. It seems unlikely, however, that the morose character Jack O'Brien representing (presumably) Malick himself, played by Sean Penn, is much like the director; those who have worked with him say he is a most delightful, friendly, and helpful man.
The Tree of Life is like no other film you have seen. Its nearest equivalent I know of is Tarkovsky's Mirror (1974), another autobiographical work about a man's childhood memories, though deeply rooted in mid-20th century Russian history. Other reference points are Kubrick's 2001: A Space Odyssey (1969), for the controversial 18-minute sequence illustrating (seriously!) the evolution of the universe from the Big Bang, and Fellini's 8 1/2 (1963), for the broadly similar ending.
Apart from the portrayal of childhood in a Texan town, as seen through the reminiscences of a middle-aged man, the film is of course concerned with Big Themes, ultimately religious. The quote from the Book of Job which opens the film, "Where were you when I laid the foundation of the earth?", is God's response to Job's crying out about the woes with which he is inflicted, like the woes inflicted on the O'Briens through the death of the son. The "history of the universe" section is Malick`s illustration of this, a kind of revelation to the adult Jack in his midlife crisis. There is the theme of "nature versus grace", represented by the tough-love father (Brad Pitt) and the saintly angelic mother (Jessica Chastain). There is the conflict between our ideals and our actions, expressed in St. Paul's letter to the Romans, and articulated at one point in Malick's film.
All seem to agree about the quality of the acting. I would particularly mention Jessica Chastain; just watch how her face flickers at moments when Brad Pitt unfairly chastises one of his sons, and she feels it is not her place (in 1950s America) to intervene against her husband. Equally memorable is Hunter McCracken as the young Jack; Malick clearly has a great gift with child actors.
Even those critics who do not warm to The Tree of Life, who use words to describe it like "pretentious" (which says more about those critics than about the film), admit that it is stunning to look at and to listen to (a whole range of European composers, both classical and modern, are featured). Admittedly there is no real storyline, and, as in Malick's earlier films, there is relatively little spoken dialogue, much of what there is being characters' interior thoughts and feelings. So if you want a good strong plot, with one scene following another in temporal sequence, The Tree of Life is not for you. But if you want a personal testament by a greatly admired filmmaker, like the aforementioned Mirror and 8 1/2 , Malick's masterwork is for you. I would make just one suggestion for the DVD-watching: switch on the subtitles for the hard-of-hearing, not just because much of the dialogue is whispered, but also because you can't always tell who is speaking, and the subtitles tell you. I found this very helpful for extra understanding.
In my opinion this film is destined to be ranked alongside the likes of Citizen Kane, The Godfather, and (in our own century) There Will Be Blood as one of the Great American Films.