By virtue of it being your favorite, I would think it's doing something right. But glibness aside, you could think about as you read: Is it fully engaging you?

By virtue of it being your favorite, I would think it's doing something right. But glibness aside, you could think about as you read: Is it fully engaging you? Is it communicating a complex idea in a simple and/or novel way? Is it making you feel something? Does it make you want to do something? These are all good markers, because writing is really just about communicating ideas well. And if you don't trust your own judgment, you could look up some of the time-tested classics. Some of my favorites: The Great Gatsby, To Kill A Mockingbird, 1984 (fiction); Warren Buffett/Berkshire Hathaway shareholder letters (business/sales writing).