Well, one thing is its authenticity. It was based on the author's own experiences. Also, it portrays the relationship between the family and nature, and how they coped with difficulties. They had to rely on their own skills and the resources around them. It gives a real sense of what life was like in that historical time. It also shows the simple pleasures and values of the people then, like family togetherness and hard work. This all makes it special in historical fiction.
The detailed descriptions of pioneer life. It shows how families survived in the woods, like making maple syrup and building cabins.
The fact that it brings the past to life. It doesn't just talk about historical events in a dry way. Instead, it lets you feel like you're right there with the Ingalls family. You can see how they cooked over an open fire, how they made their own clothes from animal skins. And it shows the community spirit of the time too. People helped each other out. All these elements combined make it stand out in the genre of historical fiction.