I'm missing something here. I had absolutely no empathy with or sympathy for the main character, I have no picture of him in my head, I didn't believe in him, I didn't understand him. I didn't care about him or any of those around him.
My conclusion is that this is not well written. It paints a rich picture of the Poland of the period; though I have no idea if it is historically accurate, it was at least interesting. That seems to be the strength of the author and the point of his work. In this book, at least, he has signally failed to create a character. I'd love to see the movie, Alan Arkin is a great actor, and I couldn't help thinking that it would work better on the screen.
In short, disappointed. If you want to read a good book about an artist who can't keep his dick in his pants, even more unpleasant, but nonetheless makes you feel for him every step of the way, try Simenon's The Heart of the Man