So, what the hell is this? Is it an episode of Black Mirror, a movie from the Black Mirror crew, or something else? It feels like a Black Mirror episode, albeit a movie-length one. But I've noticed in the couple of days since I watched it, that I refer to the experience as "playing", as in "when you're playing it, if you choose X". So maybe it's just a fancy video game. I'm at a loss for how exactly to evaluate it.
In case you've missed the hype, "Bandersnatch" is an interactive movie that works like a Choose Your Own Adventure book. Every once in awhile, a choice of two items appears on the screen. For instance, at the beginning, our young hero, a games programmer, comes down to breakfast. His father asks him what he wants, Frosties or Sugar Puffs, and those words are shown at the bottom of the screen. You choose one, and the story proceeds, informed by your choice. (I took Frosties.) The choices get increasingly troubling, such as deciding which character will kill themselves by jumping off a balcony. This being Black Mirror, there are no happy endings ... although there are apparently at least five possible endings, none of them work out well for the protagonist.
You can see why this is hard to evaluate. Just on a basic level, the "Bandersnatch" I saw, which followed my choices, is different from the one you will see, or even from any subsequent viewings by myself (there are supposedly over a trillion unique permutations). There's no use judging the plot, because it's never the same from one viewing to the next.
The question thus becomes, does this stunt have value beyond the playfulness of its construction? At least in the one time I watched/played, the movie was seamless. There were never any glitches to remind me I was watching/playing a movie that was making decisions every step of the way. Because of that seamlessness, it's easy to forget the technical aspects. Honestly, though, I can't say "Bandersnatch" had much going on beyond the trickery, which isn't to say it was pointless ... it was fun, even intriguing. The best part came when the hero starts thinking he is being controlled by some force, some other people. At first, it just seems like part of his growing alienation and paranoia, but then he gets specific: I don't know why I chose Frosties over Sugar Puffs, I just did, someone controlled my decision. And the viewer realizes that we have become part of the story, for we are the ones controlling him.
It's all perfect for the kind of endless examination of minutiae that flourishes on the Internet ... within hours of its release, people were posting flowcharts of all the possible choices, and spotting the frequent Easter eggs, many of which are call backs to other Black Mirror episodes. This is not where I would suggest people start who are new to Black Mirror ... it is far from the best episode. But it is a different kind of viewing experience, worth a shot (or two, or five, or a trillion).