A Beautifully Hypnotic journey to the edge of Self. You could never accuse Andrei Tarkovsky of not giving the viewer breathing space (read: Thinking) within the walls of his films. I have always found Solaris to be a good test of anyone's ability to think, and more importantly, to look at what is being presented to them. Like all the best art, it works on many levels of the subconcious in a sublime fashion.
Solaris, like Kubrick's 2001, is often described about being "...a long film about nothing!" Nothing because the viewer has failed to detect or take anything from the piece. These are people who go to art galleries and spend more time reading the little 'synopsis' cards that accompany the actual paintings rather than 'look' at, or into the work.
So, what am I saying? I'm saying that Solaris requires Thought, Patience and a love of Visualization over explosive set-pieces.
And when you finally 'see' the film: It's magic!