Car and Driver about the making of a chase scene for the movie Fast and Furious 6. What struck me was the amount of computer generated images (CGI) that were being used in something as mundane as a car chase. But the filmmakers were able to use CGI to enhance reality. For example, the scene was set in London but was filmed in Liverpool. To get the right look they used CGI to put in appropriate-looking buildings along the street.
Pretty much anything can be shown on a movie screen with CGI. Probably the best CGI is when the audience says "That was CGI?" Like the 6,000 Riders of Rohan in the Lord of the Rings: Return of the King (a 10-year-old film, by the way). Of course, if there's something on the screen that doesn't happen in real life, everyone will know it's CGI (like the trolls in the LOTR movies).
So here's the challenge for filmmakers: use CGI to enhance their story telling, not dominate it. Remember Star Trek: The Motion Picture? Awful movie. What happened was the director thought he was making a The Sound of Music in space and his beautiful special effects (which in the pre-CGI world probably cost a bunch of money) would hold the movie together like the lovely images and sounds of singing children in Salzburg. At least that's my opinion. And yes, they were both directed by the same director (who, I just found out, also directed the original The Day the Earth Stood Still).
So the lesson to take away is, yes, you have amazing special effects these days. But you still need to tell a story that entertains. And for writers, maybe you can write beautifully, but you still need to entertain your audience. Either that or write poetry. It's not the mechanics of writing (or filmmaking) that will hold an audience, it's the story, characters they can believe in and love, and a quest they want to see taken to the end.