The book is much better! Tarkovsky has this peculiar style of movie production, he focuses on the philosophical / existential issues from the original books and brings them to absurd levels. His movies are almost unwatchable. Strugatsky tend to ruminate sometimes, but Picnic is still solid sci-fi.  I'm glad you enjoyed it! Though it's not my favourite book by these authors, that would be Monday begins on Saturday. Otherwise, probably the Kid from Hell - it's, in my terms, quite "motivational". Plus, the MC served in an elite army unit called the Fighting Cats ;)