Solaris is often referred to as Tarkovsky's response to Kubrick's 2001: A Space Odyssey. Certainly both engage with the grandest end of science fiction and their circular space stations are strikingly alike. But comparing the two is properly useful only to see their differences more clearly.

Solaris, unlike 2001, is only slightly concerned with narrative progression, or satisfaction, and the first function of its visuals is not to please the eye. That is not to elevate it above 2001 necessarily, but to emphasise that Anglophone films, with their need to entertain, amidst whatever else they do, are perhaps always more bent away from the arthouse than towards it. Tim Roth was asked in 1999 which directors inspired him. He replied, "The arthouse tradition: Tarkovsky, Antonioni - I miss silence. I miss silliness."

There is a lot of silence in Solaris, minutes of it at a time, and Roth was right to link it to silliness. At the time, it seems monstrously overlong. Clearly the establishment of a languorous atmosphere, in which to consider the text's philosophical considerations, is necessary, but not this languorous. It takes Tarkovsky three-quarters of an hour to get us to the space station, so busy is he exhibiting the detached, aphoristic language of the film and the ideas with which it is aiming to engage. The problematic part of the equation, however, is that the characters on Earth seem little different when they get into space.

The questions posed by the plot are simple and profound, but the plot itself is complicated. I've no hesitation in revealing it, because the substance of the film does not lie there, but in its implications. In the future, Kris (Donatas Banionis), a psychologist, leaves Earth for a space station, observing the sea of Solaris. On arrival, he discovers that one of the three people there, Guibariane, has killed himself. It transpires that the sea has made some form of contact with those on the station - it can invade them and alter them.

He encounters his first wife (Natalya Bondarchuk) and falls in love with her again. But she turns out to have been, as Dr. Snauth, the station leader, tells him, "the materialisation of the person you thought you knew." In a video message to Kris, Guibariane asks, 'Have you seen her?'. The "her" seems to refer to the woman who appears in Kris's room in one of the film's remarkable transitions from black-and-white to colour. Later, she is seen to meld with Kris's other woman and so Guibariane's question takes on, as much of the film's script does as it progresses, a further meaning: have you seen her for what she is?

Eventually, we discover that she is a product of the sea. She leaves for his sake; he returns home. The final shots of the film make all clear. They establish what we have come to suspect, that the Earth home is, in fact, on an island in the Solaris sea. All the characters must therefore have been affected by the sea's infection of them long before the film opens, which is why Solaris is not concerned with narrative satisfaction - there is none to give. The arc of discovery is on the part of the audience, not the characters.

There are problems with this approach, for though it proffers a film which yields its richest fruits in the mind after watching, that only partly compensates for the sometimes exasperating viewing experience. It has the unwinning combination of being both slow and too long.

Cinematographer Vadim Yusov and Tarkovsky are said, in one of the interviews accompanying this release, to have made some scenes too long, as their votive offerings to the studio, in order to protect those they really cared about. They went too far: it is not just that Solaris does justice to the intellectual potential of sci-fi but not to the narrative or entertainment potential - that is clear from the comparison with 2001 - but that its slothfulness diminishes the intellectual potential. This does, however, leave plenty of room for the film's remarkable sound mix, use of colour and elegant shot-making. The paucity of cuts, predominance of slow pans and tracks, use of blackouts and the general movement of fluidity are entirely appropriate and eloquent.

The dialogue is not significant, the words being more a necessary currency than something of value. It is the considerations they spark that are meant to be the weight of the film. Here again, frustrations. The philosophical points, such as what we fear is part of us, that our view is always subjective ("What would I see?", Kris asks, about the sea. He is told: "That depends on you") and limited are woven into the film's fabric.

There is a purity in staying within its own world, as circular as the space station. But limitations also: the ideas are hardly new ones and their handling invites you to accept the film as a piece rather than examine its assertions. Fascinating and influential as it is - Blade Runner, Brazil and The Fifth Element are all in its debt - I found it too flawed to accept wholeheartedly.

"Don't turn a scientific study into a bedroom story," Kris is told by Dr. Snauth. The reverse also applies.