The language and meaning of the book are usually clear and easy to understand. There are some worlds that the reader may want to look up depending on the strength of his vocabulary.
The meaning can be a little confusing at various parts like with the Peter Stillman dialogue in City of Glass. He speaks in thyme. There is a lot of play on words in City of Glass with a lot of rhyming of words with both the elder and younger Stillman. In Ghosts, Blue balls asleep playing a game with colors and naming all the items he can think of that are certain colors. However, the language fits the kind of novel that Auster has written and more or less show the psychological state of the characters.
City of Glass