I did like Tarkowsky's Solaris, though it's not really an adaptation of the book (an impossible challenge, I believe), but another brilliant and personal masterpiece of the great russian director. When I saw the american version cassette in the video club, I took it, hoping at least a few special effects on the phisical transformations of the planet. I was thinking, perhaps, in the star trip of Bowman, though I know Soderbergh is not Kubrick.
But the american film seems to have been made out of Tarkowsky's rather than from the Lem's book. And that's all: an average american perception of a russian genius metaphysics -nothing at all, but boring.
The films don't deserve the book, but least they are ways to make the world speak about Lem, a great master of two centuries.