Here is an interesting take on his character:
"Beyond any doubt Túrin is the protagonist of Children, and the hero of the tale if it has one. He has the interesting trait, common enough among ‘men of honour’ in primitive cultures and still more in their mythological traditions, of having the strictest scruples without any actual morals. He is stubborn, stiff-necked, wilful, impulsive, violently touchy, immune to good advice, and prone to murderous rages against his closest friends; I can barely resist adding, ‘And those are his good points.’
I am not sure that I agree entirely with this opinion. Turin is certainly a hero; but he is much more complicated that the stereotypical mythic hero; his story is taken from Kullervo's story, but he has nearly nothing in common with him as a character.
I think that the good beginning would be to consider whether Turin has strong or weak will. He certainly is ridiculously brave; he is able to take command of the most improbable groups of people, from a band of outlaw to an elven kingdom. It would seem that his will is impossibly strong. But, when we consider his command over his own life, we can begin to wonder whether he has any will at all. Let us consider his kinsmen, Tuor and Earendil; both knew what they wanted, did everything to reach it, and succeeded. His father, Hurin the Steadfast, possessed an unbreakable will. Released by Morgoth he wanted only one thing - to punish everyone who failed his son. He, old, broken, alone, wanted to destroy two still powerful kingdom - and did this. Not one of those who failed Turin survived.
What did Turin want? What was his aim, his goal? Perhaps to regain his father's kingdom in Dor-lomin? But he did nothing in this direction. He was ruled entirely by circumstances.
When we consider the morality of his behaviour, we see something similar. Sometimes it seems that he is amoral, in other moments - that he is ruled entirely by morality. The answer is simple - he as a child has been taught certain rules of behaviour, and they rule him even more than his passions. He does not consider or debate them; there is no man less given to introspection than him. He simply follows them.
His most powerful instinct is the need to defend women. At times it seems even morbid. When Saeros provoked him, he had been thinking for a long time about the fate of his mother and sister, and his inability to help them. We are not told what his "dark thoughts" were exactly, but his explosion, when Saeros said: "'If the Men of Hithlum are so wild and fell, of what sort are the women of that land? Do they run like the deer clad only in their hair?', suggest that they must have tended in that direction.
Turin seems nearly unable to love; his tendency to defend women seems nearly to have taken the place of the love. When Finduilas tells Gwindor that Turin doesn't love her, she adds:
'But also he is merciful,' said Finduilas. 'He is not yet awake, but still pity can ever pierce his heart, and he will never deny it. Pity maybe shall be ever the only entry. But he does not pity me. He holds me in awe, as were I both his mother and a queen.'
Maybe Finduilas spoke truly, seeing with the keen eyes of the Eldar. And now Túrin, not knowing what had passed between Gwindor and Finduilas, was ever gentler towards her as she seemed more sad. "
Another reason why his instinct to defend women seems so impersonal is that for Turin nearly all people are simply figures upon the stage of his mind; they appear and dissappear; he reacts to them as long as he sees them; but then they are put away and replaced by new ones; and he forgets them. The only people he treated as people, that is as independent actors with life separate from him were, I think, his family, Beleg and Niniel.
"Coming suddenly out of thought he looked at Beleg, and said: 'The elf-maiden that you named, though I forget how: I owe her well for her timely witness; yet I cannot recall her. Why did she watch my ways?' Then Beleg looked strangely at him. 'Why indeed?' he said. 'Túrin, have you lived always with your heart and half your mind far away? As a boy you used to walk with Nellas in the woods.'
'That must have been long ago,' said Túrin. 'Or so my childhood now seems, and a mist is over it - save only the memory of my father's house in Dor-lómin. Why would I walk with an elf-maiden?'
'To learn what she could teach, maybe,' said Beleg, 'if no more than a few elven-words of the names of woodland flowers. Their names at least you have not forgotten".
If Proust wrote "Remembrance of Things Past" Turin could call his memoirs (which he wouldn't, of course, write) "Forgetting of Things Past - With pleasure". He does not remember his childhood, and he does not regret it.
Turin was perhaps the only man behaving according to the Behaviourism of Skinner. A stimulus causes response, there is no internal debate, no decision, no will. Glaurung is able to play on him like on an piano; he always strikes the correct keys and Turin dances to his melody.
Turin was a man who should have been married to a wise woman; he was unable to think for himself. He was not stupid; he simply refused to think and relied on his instincts. He would never really obey any man, since one of his instincts was to take command over men. But he needed someone to command him. I think even the girl he saved from Forweg could do what she wanted with him - if she knew how to push the correct buttons. But the first woman who pushed them was Niniel - she certainly knew how to influence Turin.
What did Turin think of himself? That is easy to guess; he thought himself the best of men and greatest of heroes. He couldn't bear a thought that he was something else; when he killed Beleg he went mad; when he learned about Niniel he killed himself.
If so, why is Turin a hero, and not one nonenitity among many? Because his gifts and talents were greatest of all heroes of Silmarillion, greater, I think than even Feanor's, and his instincts were, after all, right - even if he lacked prudence in following them. And he was certainly not afraid to do the right thing.
You can consider Turin improbable; but he is all to real. Certainly, he isn't a good captain - that is why he loses. But the fact that people follow his is quite probable - he is certain of himself; he has no doubts. They are in a desperate situation and he is the only one with a solution, even if a mindless one.
Compare him with Hitler - an aimless drifter, lacking a will even to find a work and get a life, who didn't get a job as a theatre set designer because he was afraid to go to interview - but who was able to capture a whole state and lead it into disaster, with no one to oppose him. If it was a book you would certainly call it improbable.
Obviously Turin is incomparably more gifted than Hitler. He is actually quite a good captain in short term, able to set an objective and follow it. He is certainly intelligent, brave and decisive.
But he lacks some higher element, which would allow him to use his gifts towards some aim. This is why it is a tragedy; we see talents misused, life wasted.
Aristotle - Poetics
Turin is certainly in many aspects a modern man; Musil's "Der Mann ohne Eigenschaften". But he apparently was born in XIX century. His instincts are all about honor, glory, duty etc, in the world in which they have little place. And he is unable to reach deeper, to the sources of those things he holds dear. He is remarkable for one other thing - he does not care for Valar, and even less for Eru. He intends to win or lose by his own remarkable strength. Earendil or Tuor can go on in the face of defeat, because they see a hope beyond the world. Turin cannot.
"Children of Hurin" can be said to be a story about rape. The most iconic image is a naked woman running through the woods. This reminds of a story about Nastagio degli Onesti from Boccaccio's Decameron, which has been beautifully illustrated by Botticelli.