1. It's very good and you should go see it. I expect it will leave theaters soon (and is only showing in LA and NY as far as I can tell) but then you should be able to watch it on Amazon or something.
Everything after this will assume you saw it and don't mind spoilers.
2. The reviews of it are dreadfully misguided.
It's clear the movie is in some sense about being a fan. After all, it's about an obsessive (white male 25 year old) nerd and his favorite television show.
From the AV Club Review:
The film clearly sees James’ devotion as a metaphor for the intense relationship some fans develop with their favorite entertainment, their loyalty to the work shaping (and narrowing) their worldview. At the same time, the character reflects nostalgia for an era of less hostile fan culture;No, that's not what the text supports. The first five minutes of the movie are about this intense, one-sided relationship. That start shows James watching an episode, then recording a review of his reaction from seeing it for the dozenth time, then telling his forum board online about it, then showing is parents a poster-board of his theory of how the metaphysics in the show work. To his unimpressed parents, who want him to focus on more productive pursuits.
It's very cliche and awkward, and so painful I wanted to cut my losses and leave the theater then. (I'm also not unaware of the comparisons between what he's doing and pursuits like this blog, but we'll get to that later.)
Everything after that is different. We understand he loves the show because it's the only art his parents ever exposed him to. His forum board friends become a metaphor for insularity when its revealed they were just his fake-parents pretending to be online accounts. His reaction to finding out that all of Brigsby Bear was a fraud - that his kidnappers made it, that only he ever saw it, that there won't be anymore now - is definitive of James entire attitude to life.
"Can... I make Brigsby Bear?"
James wants to be a generative force. He also wants to share it with his friends and people online. There's none of the bitterness or denial you'd get in a cliche story about nerds here.
So instead most of the movie is about James going on an authentic Artists Journey. Most movies about artists focus on their Lone Genius and their Passion for Beauty and how no one understands them.
James makes Brigsby Bear in order to make friends. It's a passion he can share with them, and they also like the idea of making something cool, and they contribute their ideas and tools and time, and it's a fun tight-knit tribal group. And this is much more familiar to how most impassioned projects get off the ground - because working with the other people on it is fun. All the wacky ideas his friends toss around are just so true to life (coming from a comedy troupe that had been together since 5th grade.)
In many ways, Brigsby Bear is more reminiscent of fan-fic communities, which are both heavily inter-connected and based on feedback from other people, and generative in making their own art. And looking at these communities, you can see it takes a very short time before the community is much more important than the fandom, which come and go as passing fads really, from SuperWhoLock to Amenta.
3. Another important point about art is that while the movie depicts all this positive bonding going on, it never shies away from the fact that Brigsby Bear was originally bad. As his biological father says to one of James' friends "These aren't collectibles. These are tools that sick people used to control my kidnapped son."
If the authors did not have a point to make with Brigsby Bear's disturbing origins, they would just have not included insane kidnappers.
The point is, that even though Brigsby Bear comes from a bad place, these bad things are part of us and what we make our art out of. Maybe you use art to express trauma that happened to you. Maybe your art is about desires you have, ones that you know would be toxic or unhealthy to pursue. It's important to know these knots are things you need to work through, but it's also important to not repress them. If this evil thing is what you can make art out of, art that fascinates the world, then you just gotta go for it.
4. A weird tangent in the same AV Club review.
(In one of the more far-fetched developments, strangers also un-ironically embrace the campy show uploaded onto YouTube.)For one, the world-en-masse discovers your (art/startup/political campaign/personal sob story) and responds with free money is already a classic trope of triumph stories, from Silicon Valley to West Wing to It Could Happen To You to Entourage, and on and on. It's a faceless way for Big Other to shine approval and success on the heroes. It's not my favorite trope, but it's not at all a surprise in a movie like this.
The interesting word is their use of "un-ironically." Since to my eyes, the whole "youtube generation falling in love with a fake 80's television show" complete with hipsters coming up to you in Home Depot to say how awesome it is, is exactly what I think ironic appreciation is. This is the same thing as bros liking My Little Pony or Chewbacca Mom going viral. So the success fit in exactly with our own world's reaction to outsider art.
But a friend pointed out that this isn't what irony used to mean. "Ironically liking something" meant performatively making very clear that you think its bad. You just can only demonstrate your disdain by highlighting the thing in the first place. This is the Gen X version of irony, and is exemplified still in things like Elizabeth Warren writing tweets in Donald Trump's style. I'm not a fan of this. Sad!
Instead, the defining line for why the world at large likes Brigsby Bear, is when James' sister listens to a song his fake-dad recorded for the show. "This is the worst song I've ever heard... I kind of love it."
So we've had the transition from "performatively dislike something by highlighting it" irony to "appreciate the sincere soul behind bad things" irony.
This elevates irony from the confines of belonging to an arsenal of rhetorical devices to the independent status of a means of philosophical inquiry and revelation. It is obvious that this theory is, because of its abstractly all-inclusive claims, difficult to pin down into a concrete definition or to put into literary practice. To a large degree this is its audacious point: by offering the means for its own explosion, it guaranteed its very indestructibility in a never-ending process of reflective distancing. As such, Romantic irony is the intellectual response of the (Romantic) human mind finding itself alone and without external guidance in an infinitely complex and ultimately unknowable world in which the only way to assert any kind of independence and authority is to engage in the conscious act of hovering between opposites (which irony allows), affirming and negating at the same time. Although the paradoxical totality afforded by this approach strives toward divine omniscience, it equally engenders the absolute relativity of all values and opens the door to nihilism. A melancholic, even desperate, viewpoint developed quickly that understands irony as a last resort to make bearable the Romantically contradictory experience of existence, which, in its negative manifestation, finds expression in the notion of Weltschmerz (see Melancholy).Encyclopedia of German Literature
5. The above does hit on the main recurring motif in BB. A situation is presented that easily threatens to be embarrassing for James: he goes to a party for the first time, he tries to explain Brigsby to the detective in charge of his case, or his sister listens to the only music he's ever heard. And each time... they show warmth and openness and the desire to find something good in James. The entire movie (after the painful start) is always this positive, using the threat of cliche cringe humor to make you relieved when there is charming happiness. (And the subversion is often fairly hilarious, making most of the best jokes of the movie.)