For about half of its first season, Tokyo Ghoul runs the risk of letting its own worldbuilding get the better of it, by giving us a main character who's severely upstaged by the story he's in. Then the show manages to tack against the wind of its own issues, and goes from being a near-miss to a very palpable hit. The hard part for some audiences, I suspect, will be getting to that tipping point. I know my own patience was tested at times, even when I knew full well that was deliberate — you don't show someone pulling themselves up by their own bootstraps all in one go. The question is, is it worth the payoff? In this case, I think it is, and not just because a good deal more of this story awaits us down the line.
Surprise! You're dead!
Looking back on it now, a big part of the whole point of Tokyo Ghoul is that its main character mans up from being a milquetoast. Kaneki, the young fellow in question, is a wide-eyed sort whose idea of a good time is curling up with a warm book. He lands a date with another booklover, a lady named Rize, and he's ecstatic about the prospect of making a sincere connection with a member of the opposite sex. That lasts until Rize tries to tear his throat out. She's a "ghoul", one of a human subspecies that feasts on human flesh to survive.
Kaneki does not die, but ends up being saved by having Rise's organs transplanted into him. He's now half-ghoul, half-human, as outwardly evidenced by the way only his left eye (as opposed to both) turns red-on-black when his fleshlust is aroused. Human food has become revolting and inedible; only sinking his teeth into a living specimen will do. (Those who are put off by gore shouldn't even think of watchng.) But the idea of devolving into a mere monster is repellent, and he's prepared to let himself die rather than kill another human being. The other ghouls he runs into, with their turf wars and their propensities for easy violence, are only too happy to make a patsy out of Kaneki's ethics.
All that changes when Kaneki ends up in the care of a small cadre of ghouls who understand that not everyone cast into the role of ghoul wants to fulfill it. One is the fatherly Yoshimura, owner of a café named Anteiku that functions as a kind of safehouse for ghouls. (In what I can only take as a nod towards the idea that coffee is the beverage of civilization, Yoshimura provides Kaneki with a specially formulated brew that keeps his thirst at bay, a la the serum used by Blade in Marvel Comics lore.) Under Yoshimura, Kaneki can work at what looks like a perfectly respectable part-time job — the better to convince his happy-go-lucky human friend Hideyoshi that everything in his life is just peachy.
The other key ghoul in Kaneki's life, Touka Kirishima, another Anteiku member, is as good at keeping one foot in either world as Kaneki is not. She's able to keep her existence as a ghoul boxed up tidily enough to be able to attend school; "assimilationist" would be a good adjective for her outlook. She's prickly and hot-tempered, not amused by Kaneki's overall hesitancy to deal with the ugly realities of ghoul life. Most other ghouls are not your friends, and at some point Kaneki's going to have to bust out his "kagune" — a set of winglike appendages that ghouls use to fight — and take a life to protect one close to him, or even his own. On some level, Kaneki knows this, but he's not yet capable of living by it.
Level up or shut up
I mentioned before how one of the possible drawbacks to the way the show is constructed is that so much of what goes on around Kaneki is more interesting than he himself is. Once upon a time, I formulated a theory about why many of the earlier animated Disney movies sported relatively bland main characters, but eccentric and striking supporting characters. (Cinderella loses out to the mice; the dwarfs routinely eclipse Snow White.) The problem's less egregious now — nobody would ever think Belle of Beauty and the Beast as a blank slate! — but it seemed the reason behind that was to hedge bets in terms of who to make sympathetic, relatable. If your main character is a cipher, but a pleasing one, it's easier to project one's own feelings onto them. The tics and eccentricities can be relegated to the people around him or her. The production as a whole doesn't feel flat, even if the person at the center of it is.
I'm not a fan of the idea that in order to empathize with someone, he has to be "like us", or that he has to represent some least-common-denominator concept of what the audience might be. People pay attention to a character not because he's "like us" or even because he's good, but because he's interesting; we wouldn't have seen the kind of turnout for Hannibal or Game of Thrones if that weren't true. Kaneki doesn't really start to become interesting until around halfway through the season, because the existential dilemma he finds himself in is paralyzing to the point where it becomes overwrought.
But to his credit, he breaks out of it — and again, the point is that it doesn't happen all at once, but by slow degrees. I think now there's more evidence for this in the earlier part of the season than there might first seem. Early on in his introduction to ghoul society, Kaneki forms a big-brotherly relationship with Hinami, a young ghoul whose mother is eventually killed by the ironically named "doves" of the CCG (the human agency responsible for taking down ghouls if they interfere in the affairs of mere mortals). He's willing to form the kinds of emotional attachments that will, in the long run, demand sacrifice on his part. Kaneki also bears witness to other examples of that behavior, and in time seeing such things helps galvanize him further. Nishio, the ghoul who assaulted Hideyoshi, also has a human girlfriend, one that has made more than a few sacrifices for him, knowing full well what she was getting herself into as a result. When she's kidnapped as part of a plan to lure Kaneki into the jaws of another ghoul, a would-be aesthete longing to savor the taste of Kaneki's hybrid flesh, Kaneki takes his first concrete steps towards asserting himself.
The grass is also brown on the other side of the fence
There's never any question Kaneki is a good person and deserves the label of protagonist, but that's because of how he goes about trying to do the right thing, not because of what side he's on. Further support for this distinction comes by way of the people in the CCG. Among them are investigator Kureo Mado and his partner, Kōtarō Amon. The latter is a square-jawed, workmanlike fellow, but the former is a classic example of character design being destiny — he looks like Doc Brown with one popped eye and a smile that always looks like he's about to bite into something. Hunting ghouls is all he lives for, and it proves to be his undoing when he relies a little too heavily on the "quinque" (the bioweaponry CCG agents use against ghouls) and gets taken to pieces for it. But how the show handles his death is fascinating: those who survive him at the CCG, including Amon, are deeply affected by the loss. He many have been despicable to us, but to others, he mattered. Even someone as unsympathetic as Mado, the show seems to be arguing, will be lamented by someone somewhere. It's not just the good guys and the beautiful people for whom others will shed tears.
A tack like that is difficult to get right. It runs the risk of feeling like a mixed message, instead of an attempt to see things more holistically. But Tokyo Ghoul manages not to fall into that trap, and I think at least part of that lies in how the storytelling and worldbuilding are complementary, not contraindicated. Worldbuilding works best when it's a two-way street — when how the setting is embodied in the story gives the characters something to do that enriches that setting. What I saw of Monster Musume shot itself in the kneecaps by not doing this: the worldbuilding set up by the show (nonhumans live amongst us) wasn't leveraged in a meaningful way by the main storyline (dimwitted soft-porn comedy), and so all the stuff that actually seemed worth telling a story about was off in the margins and sidelines. In Tokyo Ghoul, all the important stuff is front-and-center, even if the character they chose to be the linchpin for all of it doesn't at first seem up to the job.
Anime excels at being a medium for delivering stories with both stylized settings and memorable characters, but the hard part is ensuring the former doesn't blow right over the latter. I'm most interested in a story that is curious about the implications of the things it brings up, and employs characters that embody the story's curiosity. If you started watching Tokyo Ghoul and bailed in frustration because you were interested in what was going on but felt the main character was a wimp, I'm not sure I'd argue with your interpretation. But I would also argue that you'd have missed out.