I'm going to explain the plot now in case you haven't seen it, in which case you probably shouldn't be reading this anyway because I'm going to spoil the shit out of its final act.
It's the near future and Johannesberg is having great success with its shiny new robotic police force created by young scientist Deon (Dev Patel) who works for a manufacturing company under Michelle Bradley (Sigourney Weaver). He has to deal with the scrutiny of Vincent (Hugh Jackman), a brawny weapons designer whose hulking combat droid the "Moose" is given less favour than Deon's smaller, cuter kin. Cut to bumbling criminals Ninja and Yolandi (played by South African rap-rave group Die Antwoord playing themselves [?] in a weird bit of meta-casting) and Yankie (Jose Pablo Cantillo) as they are thwarted by the robotic police force and later threatened for a large sum of money by a brute of a criminal whose English is so bad it requires subtitles for the whole film. They decide they need a way to bypass the robot police and kidnap Deon just as he's nearing a breakthrough on sentient A.I. and BAM! Chappie (Shartlo Copley) is born into a wild and crazy new world where he must grow, learn, and think for himself.
The film deals with the typical artificial intelligence questions of what makes us human and how do you quantify a soul, and it succeeds largely on those fronts. But then the ending happens, and that's where I could tell most of the audience started to tilt their head and look at the screen funny. In short, it takes a rather daring and fantastical turn.
Spoiler Warning . . .
Chappie is living on a short time frame; his battery has been fused to his chest cavity meaning it can't be replaced and once it runs out, he dies. Grasping with the concept of imminent death the way most people would, he desperately searches for a way to insert his consciousness into another robotic body. While arguing with Deon at the facility where he was created, Chappie steals the neural helmet used to up-link a human brain to Vincent's skulking war machine, even though Deon insists it's impossible to transfer an actual consciousness. As Deon also says earlier in the film, however, any organism with the mind of a human and the processing power of a computer would be able to learn and think faster than any human could ever dream. A few trips to the Internet later and Chappie finds a way to use the helmet to map his neural consciousness.
Shit inevitably goes down into a climax that involves a massive firefight between Ninja and his gang, the crime lord threatening them, and Vincent's "Moose" robot with poor Deon caught in the middle. Yankie and Yolandi (who has been a surrogate mother to Chappie) are killed, Deon takes a bullet to the gut, and Chappie wrecks the Moose before beating the shit out of Hugh Jackman. In a desperate bid to save Deon's life, Chappie uses his new-found wisdom and neuro-link helmet to transfer Deon's consciousness into the body of a robot, who then quickly transfers Chappie into a newer body. It's also revealed at the end of the film that Chappie had made a backup of Yolandi's consciousness while testing his helmet, and they begin creation of a robot body to "rebirth" her as well.
The issue I imagine most people will have with the ending is that it seems too fantastical and it happens too fast. The whole premise of the film is based around creating a computer program that perfectly mimics the human brain so as to develop its own personality and character. Science fiction has dealt with that idea for decades so it's not a foreign concept (Spike Jonze's Her presented it in a wickedly touching way), but the notion of transferring the human mind into a machine is a little more tricky. It's a difficult concept to grasp - reading and then "copying" the entirety of what makes a person a person and somehow transforming it digitally - and Chappie glosses over the technical difficulties rather quickly (it takes Chappie all of five minutes and a montage to accomplish it). The audience is asked to suspend disbelief to believe this robot has the mind of a person, and then within the last ten minutes of the film asked to suspend disbelief even further to believe a human mind - a very ethereal and intangible thing - can be transferred into the body of a robot.
I think it makes people a little uncomfortable to think of a human mind in the body of something that isn't human - like a perversion of nature, far different from creating a mind from the ground up to exist in a mechanical body. It brings about feelings of claustrophobia and isolation, of being trapped in something foreign. It asks too much of the audience. There have been other movies that have toyed with the idea, but the less fantastical and more rooted the reality of the film's world, the more difficult it is to grasp the prospect (Wally Pfister's Transcendence didn't connect well with audiences, whereas no one blinked at Zola in Captain America: The Winter Soldier because it was based on a comic book). Chappie, like the rest of Blomkamp's films, is heavily rooted in reality, so the leap from grounded to fantastical is rather severe.
But the more I think about it, the more appropriate it seems. I would even go so far as to suggest it might be the only inevitable ending the film could have.
The film begins as the story of how a man created a machine with the mind of a human, and ends with a robot creating a human with the body of a machine (I leave it to you to ponder whether or not they're the same thing). When you think of it in comparable terms, it suddenly doesn't sound as far fetched. The film makes the point (as does every science fiction film involving robots) that artificial intelligence would no doubt develop in leaps and bounds just because of the computing power machines are capable of. Deon even says while describing the program he's developed for artificial intelligence that whatever mind is created as a result will be vastly smarter than any human in history and will be capable of learning and retaining information at an exponential rate. By the simple nature of robotics, it therefore makes sense that although it took mankind an unfathomably long time to evolve to the point of being capable of replicating the mind digitally, it would only take a robotic mind that has access to all the information in the world hours to accomplish the same feat in reverse.
And that is what I believe the true point of the film is. It's not a story about a robot that gains consciousness, but rather the story of the end of humanity. Deon is the result of millions of years of human evolution who creates a robotic human mind thanks to the communal intelligence, research, and innovation of the entire human race and scientific community that came before him (because science doesn't occur in a vacuum, it's built on the foundation of the accomplishments of everyone that existed prior). Chappie, the infinitely intelligent result of this impossible accomplishment, achieves the next "impossible" feat - transferring human consciousness into a robotic body - within a few days of his inception. Chappie then uses his breakthrough to save Deon's life by removing his maker's mortal flesh and replacing it with immortal metal. In essence, Chappie removes the fear of death from Deon by making his human body obsolete, thereby removing part of his humanity; he also goes about using the "backup" of Yolandi's consciousness to effectively raise her from the dead as well. Chappie has ushered in a world where death doesn't exist, and thus has changed the very essence of what it means to be human and the course of human history.
It's a wide open ending, and Blomkamp has said he created the film as a potential first chapter in its own trilogy, so I can only imagine where its sequels might go. While the attempt to create a robot version of Yolandi may seem a tad much, I personally think it's a great addition to the finale on top of Deon's own transformation. Whereas Deon is saved in the nick of time, Yolandi is clearly dead. Her consciousness is merely a "backup" copy. It raises the question of whether the robotic Deon has his literal human mind or whether it's simply a copy as well.
These are questions that don't necessarily have answers, and I believe most people will be taken aback by Chappie's ending because it throws these subconsciously existential questions at the audience in rapid-fire succession right after the climax of the film. I think it's going to end up being one of those endings that most people don't like but can't explain why, because it hits them on an almost primal level, questioning the very nature of identity.
There are plenty of philosophers that have questioned the nature of human existence, pondering what we as a species are truly meant for. Are we a disease that is meant to consume the planet and endlessly destroy itself, or are we simply an organism undergoing an awkward transitional phase before we collectively evolve into another form of being, such as robotic organisms that have shaken off the mortal coil of flesh and bone? Will we ultimately escape death, and if so, what will the cost of that be to our humanity? Is there really such a thing as a "soul" or is it simply a word meant to encapsulate all of the mysteries of the human consciousness that we haven't been able to quantify and solve?
Chappie makes us question all of this, and the fact that I'm still thinking about suggests that I must have really enjoyed it as a film. It's interesting to think that humanity will end not with a nuclear bomb or some horrible disease or terrible world war, but rather with a simple keystroke.
