Almost a year ago I posted this thread here where I called NaruHina as canon. 11 months later I feel quite satisfyingly vindicated by chapter 615 and in a safe position to declare "I f*cking called it!"
But this got me to thinking about something that gave me pause: exactly WHY do I like Hinata so much?
After much contemplation, research, soul-searching and meditation I came up with the following answer: because Hinata is arguably one of the deepest and most well-written characters in Naruto. No mean feat for what is basically a supporting character with surprisingly few actual appearances.
What I came to realise is that Hinata's character is basically defined by her relationship with Naruto. Most people would say this is a bad thing, it makes her shallow and gives her no personality of her own. But this is a very inaccurate and shallow way of looking at Hinata. While Naruto shapes and guides Hinata's character arc, she still HAS her own character arc, one of the best in the series. And why is it such a bad thing that Naruto has so much effect on Hinata when he is the protagonist of the entire series?
What is Sakura's character arc? Initially, she's in love with Sasuke because he's cool and hot and she hates Naruto because he's not and he's not. Then she realises she's useless because she never does anything and decides she doesn't want to be any more. She gets a haircut. She and Ino punch each other out of the Chuunin Exam. She starts to accept Naruto and begins getting stronger after training with Tsunade, in order to bring Sasuke back... I'm sorry, did her arc ever contain any more depth than "I want to become stronger because there's a guy I like?" Even when she set out to try and kill Sasuke herself, she eventually failed because she couldn't bring herself to do it (one of the most pathetic thing Kishimoto ever did to her). Sakura has no REAL ties to any other characters other than Sasuke and Naruto and even her connection to Naruto is really pretty tenuous. She doesn't even have a real character bond with her master Tsunade and her relationship with Ino is no deeper than "we used to be friends until there was this hot guy we both like" *PUNCH* "we're friends again!"
What is Hinata's character arc? Born the eldest child to the head of the Hyuuga clan, she is next in line to become family head, despite both her elder cousin and her younger sister being stronger than her. She is naturally shy and timid, has poor self-esteem and gives up easily, a matter not improved by her own father's disappointment with her. She also feels guilty for the death of her cousin Neji's father, who was sacrificed after she was kidnapped as a child. She finds strength from following the example of Uzumaki Naruto, a boy who is even less talented than her but is committed to his goal of becoming the strongest ninja in the village, standing up again every time he gets knocked down. She admires him because of this and tries to follow his example, leading to her confrontation with Neji where, knowing that Naruto is watching her, she commits to following his nindo, refusing to give up even in the face of death. Although the series never explicitly states it (since Hinata makes few appearances between then and her next big moment in part 2) she takes heart both from what she did and from Naruto's subsequent defeat of Neji and has become much stronger after the timeskip. When Pain attacks Konoha and defeats Naruto, Hinata is the only person who is willing to intervene to save him, taking on one of the world's strongest ninja even knowing she will die and she finds the courage to confess her feelings for him. She has won her father's approval by now and Neji no longer has any enmity towards her. In the Shinobi World War arc she resolves that now she is strong enough to stand by Naruto and fights beside him in the series' climactic battle. When Naruto almost loses it AGAIN in the wake of Neji's death, it's Hinata who brings him out of it by reminding him of his own nindo, that she also shares. Her plot arc started from her family and she resolved it both through her own strength and the encouragement and inspiration provided by Naruto. While she may love him, she's no shallow fangirl.
Hinata isn't the only character with her own arc. Shikamaru, for example, had a fantastic plot arc about coming into maturity despite his apathy, first when he becomes Chuunin and has to lead the Sasuke Retrieval mission, then when Asuma dies and Shikamaru must avenge him and accept the responsibility of protecting his unborn child. But Shikamaru's plot arc was almost completely independant of Naruto's story. It could have been part of its own series. Hell, during one of the anime omakes Shikamaru joked that they should rename the series "Shikamaru Shippuuden" with himself as the protagonist. Naruto was only peripherally involved in Shikamaru's arc; first he learned about wind chakra from Asuma (which was as much character padding for Asuma as anything else) then he showed up to try out Rasenshuriken on Kakuzu (something Shikamaru wasn't even present for as he was busy dealing with Hidan on his own). Hinata is one of the few characters who has her own arc (finding her strength and being accepted by her family) but also integrates it with the protagonist of the series.
Another thing worth noting is that Hinata is one of the most insightful characters in the series. At the start of the manga, how many characters acknowledged and were prepared to believe in Naruto? By my estimation, exactly three- the 3rd Hokage (who fits the Dumbledoresque "wise old mentor" archetype), Iruka (who at least liked Naruto, although it's honestly debatable whether he truly had faith that he could ever become strong enough to become Hokage) and, yes, Hinata, who always believed in him. One of Hinata's key early moments was in chapter 98, where Naruto met her at the training grounds before his epic fight with Neji. This was one of the few times Naruto, at the time still a brash idiot hero, admitted to doubts or weaknesses. Hinata put into words Naruto's true strength to him here, his determination to never give up which made him, even when he failed, "a proud failure". Unlike Sakura towards Sasuke, Hinata isn't oblivious to Naruto's weaknesses- she is fully aware of them and cares for him despite them. Hinata truly is the single character in the series who understands Naruto the best, she's not just a creepy stalker who hides behind things, spies on him and mutters "Naruto-kun..." to herself.
And who is Uzumaki Naruto again? The outcast child who initially more than anything else craves acceptance and is committed to becoming Hokage even though his skills are a joke. He's also the protagonist. His journey from bumbling, loud-mouthed prankster to the greatest hope for the world and the strongest ninja in Konoha is the primary arc of the series (despite the spotlight-stealing jackass that is Uchiha Sasuke). He wanted people to accept him- Hinata always did, even if she was too shy to act on it. He wanted to be acknowledged as a great ninja- Hinata always believed in him, even if he wasnt actually strong at the time. And Hinata is the girl who actually loves him, the girl who will fight despite her self-doubt if she knows he is watching, who will fight against impossible odds to protect him, who will stand beside him in the final battle. She is the character most closely tied to Naruto, despite also having a strong arc of her own. Naruto wants to be Hokage, the leader of the village- and Hinata was the character who truly showed that he could do that.
And so, despite having DRASTICALLY less page time, she is a far better heroine for the series than Sakura (not too surprising as Kishimoto has clearly expressed an open dislike for Sakura in the past). The fact that she's both beautifully drawn and genuinely likeable is just a bonus. She is SO well written that it's really a shame Kishimoto didn't realise her potential sooner.