Aesthetically, The Tree of Life is the most beautiful film I've ever seen. Malick uses unique camera angles and gorgeous, natural imagery to create a true work of art. And I'm not quite sure what his worldview is, but it is easy tell that he is very influenced by Christian themes.
Before you go see the movie, you should be aware of some things. It might feel slow at times. There is a break in the middle that shows what creation might have looked like. And there are dinosaurs... briefly. Brett McCracken gives some helpful pointers on how to watch it. The most helpful for me was to "let it roll over you." As you're watching don't focus on trying to "figure it out." Just receive it as is. I think you will find that you will enjoy the experience.
Also, here's the end of Paste's review that summarizes the basic idea of the movie:
...between shots of bubbling lava, there’s a family that you come to care deeply about, including the very flawed patriarch. The themes are grand and punctuated by a sermon on Job in the middle: Why do bad things happen to good people? What’s the value of selflessness? Do the sins of the father need to be revisited by the son? Malick touches on creation and evolution, the existence of heaven and the purpose of life, but does so as much through the humble world of Waco, Texas, in summertime, as through the direct questions from a boy to his Creator that transition between epochs. It’s as much a meditation as a narrative, asking a tremendous amount of patience from viewers and rewarding that patience with something entirely new.This trailer should whet your appetite: