Sanderson's Cosmere is an experiment in connected-universe fiction that no one else has attempted at quite this scale. Seventeen (so far) novels set in a shared universe with an overarching metaplot that most readers encounter as background mythology before it becomes foreground. The individual series work independently. The connections reward completionists without punishing casual readers.

The thing I find most interesting about it is how late the connections become explicit. You can read three complete Stormlight Archive novels before you understand that the cosmere exists as a structural element rather than a vague shared background. By the time you know enough to understand the metaplot, you're already invested in six or eight different casts of characters.

Whether this is a literary achievement depends on what you think literature is for. If scale and complexity and multi-decade planning are achievements, the Cosmere is genuinely impressive. If what matters is the quality of individual sentences, Sanderson is not your author.