First of all, I listened to the Graphic Audio version and I don’t know why they switched narrators from the main book. The narrator is fine, but pronounces everything completely differently. Sometimes I didn’t realize the narrator was talking about a character I already knew.
As for the story it’s completely unnecessary. Unlike other side-quels that deal with a very different location (and perhaps plot) from the main story, this one takes place alongside our story. It provides no drama since we know what is going to happen to the Elantrians. And a story without stakes is a pretty boring story.
Oh well, they can’t all be home runs.