Also people, please don't downvote parent. It's very fair to say this movie is boring and confusing, and I think it was the very point. Tarkovsky has this style of filming around supernatural / sf things but never actually showing them. Instead, he prefers to explore the anxiety they cause on humans, anxiety which he often represents through long waiting with deceptive conclusions, so I would say that feeling annoyed is quite what is expected from people watching them. It's art, not entertainment.