This movie is sufficiently complex that you need to watch it very carefully to be sure you don't miss anything. It's basically a demonstration of the craft of writing - and a very good one at that. Because the movie is written so well, if you think about it afterward, you'll get an excellent insight about how to advance your ideas via suggestion, rather than plodding explanations. The context shifting between what's real and what's imagined by the characters themselves (as they also think and write) forces you to really pay attention. I'd say it's definitely worth watching - especially if you want to see how it makes your own thinking react.
