On the scale of Silmarillion-chapters-turned-into-books this comes below Children Of Hurin but above Beren And Luthien, simply by dint of at least having a complete, if early, version of the story to kick off with. It isn't a bloody patch on the later, gorgeous, rich, vivid and witheringly incomplete version, and the frustration will literally make your eyes bleed, so I'm sorry about that, but be warned.