I saw it Friday, the night it opened here in town. I thought it was amazing. The movie certainly isn't for everyone, I could tell quite a few people in the theater were restless. I think they saw Brad Pitt was in it and decided to check it out.
The trailer does a great job of showing what the movie is about, unlike say The Fountain (which Tree of Life has many similarities). I would say that if you really enjoyed The Fountain you will probably like Tree of Life. The movie moves at a very slow pace compared to the trailer. The movie lacks a traditional narrative and contains minimal dialogue. There is a lot of ambiguity forcing the viewer to really have to think about what they saw. If any of those things are a turn off, skip this movie.
Without going into any spoilers beyond general plot that the trailer shows, the Tree of Life shows us life on a micro and macro scale. You see the birth and life of an individual, the protagonist. You also see the birth and life of the universe, in quite a lengthy manner. You can see some of the cosmic "footage" in the trailer.
As you can tell from the trailer, this movie is HUGE on visuals. There was not a single artificial light used in filming this movie, everything was done with whatever natural light was available. The cinematography was absolutely breathtaking. I personally enjoyed the use of powerful visuals and inventive "torpedo" camerawork to engross the viewer in the place of hefty dialogue. Will most people? Nah.
In comparing this with other Malick work, the best I have read it described is that it is different than any movie he has ever done in that there is no grand historical event as the framework for the movie. At the same time it is the movie that those have built up to. His movies always contrast the good and evil of nature and this is no different. His movies always are littered with nature shots of grass, trees, sky and this is no different. This movie seems freed from the reigns of his others without a historical backdrop (WWII, the Great Depression, landing in the Americas) as an anchor. This one really takes what Malick does an flies with it. The lack of a traditional narrative is welcoming as it allows Malick to push to new boundaries.
I'll probably be seeing it again Monday. I need more viewings and time to think and absorb it to see where it stands all time for me. The Thin Red Line is one of my top 10 movies. The Tree of Life may be better, but only time and repeated viewings will tell for sure. Great movies have great shelf life.
FWIW, there is a strong spiritual undertone in this movie. Religion plays a huge role, but it isn't preachy. As an atheist, I had absolutely no feeling that the movie was preachy or too focused on religion.