An interesting note here is that the edition most people have read was translated into English from a French edition. Lem wasn't happy with the translation, and there was a direct Polish to English translation done in 2011 which was blessed by Lem's estate, and which was released as an audible exclusive audiobook, and then on Kindle in 2014. It still isn't available in print.
There are substantial differences in the tone and even the character names.
I still like Tarkovsky's version best, even though Lem was not a fan.
That explains it. I had difficulties with the English translation. I thought maybe this is art or something. Then read it in some other language, and it was more palatable, but I do not remember the book anymore. I only remember an enormous baby rolling in the sea and lofty structures emerging from the sea as a by-product of Solaris brain ruminating.
There are substantial differences in the tone and even the character names.
I still like Tarkovsky's version best, even though Lem was not a fan.