It is the story not so much just of Turin Turambar, and the dragon Glaurung, but of all of the curse of Morgoth on Hurin's kin. It is more complete than related in the Silmarillion, and more like a standalone story. It's not as dense as Silmarillion, though still more elegaic in tone than say, "Lord of the Rings".
And yet, few writers can make my hair stand on end quite like Tolkien. I read this, and share it with you.
"Last of all Hurin stood alone. Then he cast aside his shield, and siezed the axe of an orc-captain and wielded it two-handed; and it is sung that axe smoked in the black blood of the troll-guard of Gothmog until it withered, and each time that he slew Hurin cried aloud, 'Aure entuluva! Day shall come again!' Seventy times he uttered that cry; but they took him at last alive, by the command of Morgoth, who thought thus to do him more evil than by death."
That is valor - cut off from safety or retreat, doomed to be taken in battle by an unnumbered and implacable foe - and what does Hurin shout? "Day shall come again!" And the thing is - Morgoth knows he's right, and is all the more determined to torment him, as a result. Beautiful stuff. Beautiful!