The Dark Knight Returns and The Dark Knight Strikes Again presents Batman as a dangerously obsessed, deeply disturbed, paranoid control freak who is possibly a mentally ill Sociopathic Hero as opposed to the stalwart Caped Crusader of the Golden and Silver ages and the Adam West series. This interpretation is touched on Depending on the Writer and sometimes it is the basis for whole story arcs.
Superman is also an ineffectual tool and government stooge.
Another issue of interpretation is whether he became a man the night his parents died, or if he never truly grew up.
Did Batman really beat Superman through brilliant planning and foresight, or was he just lucky that Superman had taken a direct hit from a nuke recently? Though most people seem to forget Batman needed a "walking hospital bed" just to get around at the time as well.
The book helped destroy the notion of Batman as a light-hearted camp character but he is noticeably more of a Blood Knight and borderline psychotic than even most other "serious" interpretations of the character. This part of the character is unfortunately ramped Up to Eleven in the two Miller Batman books above where the character is practically insane.
Another case is Miller using heroes besides Batman, notably Superman. Though accepted here, in later works, Miller displays a tendency to present heroes more powerful than Batman as utterly incompetent and ineffective.
This story also serves of the origin of the infamous PrepTime argument, with many Batman fanboys claiming because Batman beat Superman in this storyline, he can theoretically beat anyone.
As well regarded as the story is, it's also seen as the main reason so many writers write Batman as a psychopath, instead of just driven. It's easy to accept such an extreme depiction in an Alternate Universe, less so when it becomes the character's canon personality.
Foe Yay: Batman and The Joker. Very explicitly for Joker's side.
The depiction, manner and philosophy of the Mutants are frankly eerily similar to the more abusive "Anonymous" cells online. This is referring to the steal-your-identity-and-send-you-death-threats type of Anonymous and not the imageboard type of Anonymous.
Two-Face trying to destroy Gotham's Twin Towers with a bomb, seven years before the same thing was attempted on the real Twin Towers with a car bomb. Later on, a 747 crashes into same said towers, destroying them and setting Gotham on fire. Fourteen years before the same thing happened in Real Life.
The scene where a disturbed gunman shoots up a movie theater is disturbing in light of the shooting at a Colorado screening of The Dark Knight Rises. In the wake of the shootings, a panel◊ from The Dark Knight Rreturns depicting Batman breaking a gun in half gained popularity on the 'Net.
Mutant Gang Member: [after being attacked by a bat] It's just a Goddamnedbat.
Ink-Stain Adaptation: The story is not canon, but it has influenced the Batman mythos ever since it came out. Many fans like to think that Batman can beat Superman just because of this non-canonical story.
The Joker. His intent is to drive Batman to finally kill him and then be hunted down by the cops for crossing the line. Instead, Batman only breaks his neck enough to paralyse him. So what does Joker do? HE TWISTS HIS NECK THE REST OF THE WAY ROUND AND FINISHES THE JOB, ensuing that Batman will indeed be hunted down by the GCPD.
Batman himself qualifies in how he manipulates Superman into their confrontation entirely on his terms.
One-Scene Wonder: The tech in the space station, who appears for a grand total of ten panels, and in doing so gives important exposition regarding the Coldbringer nuke that wipes out power on the Eastern Seaboard and prompts the plot of the final act, is used to demonstrate the apathy of the news media on "technical details" and also delivers arguably the most poignant lines regarding nuclear fears of the era.
Dan: Still, my last thoughts will be a prayer for you, for humanity...and for the planet Earth. Nothing could stop the Russians from emptying their silos at us now. We'd have no defense, no way to retaliate. The one hope we have is that the decision to murder billions has to be made by a human being. (emphasis added)
Out of the Ghetto: With partial assist from The Killing Joke, Frank Miller's comic did this for Batman. Before Miller, Batman was remembered for the campy 60s TV-Show and his comics was in a period of weak sales. Miller's revision of Batman was actually the crest of an ongoing wavenote before him Dennis O'Neill, Steven Engelheart and Neal Adams brought back some of the darkness to the character but his story, as Miller is fond of saying, "Gave Batman his balls back", redefined Batman, by updating him to a modern setting of urban decay, teen gangs and vigilantism, and also giving Batman a Film Noir flavoring, paving the way for the Tim Burton films, the DCAU, The Dark Knight Saga, the Batman: Arkham Series and the DC Extended Universe.
Having Batman and Superman forced into a battle to the death was far more shocking to audiences in 1986 than it ever could be today, since, up to that point, the two had always been portrayed as the best of friends. Since then, the stark contrast between Superman's idealism and Batman's pragmatism has become an essential part of their character dynamic, and it's traditional to depict them as complete foils who have difficulty trusting one another.
Likewise, the revelation that Jason Todd was murdered before the events of the story held a lot more weight when the book first came out, since the character's death hadn't yet happened in the regular comics (A Death in the Family didn't come out until 1988), and the idea of Robin being Killed Off for Real was still unthinkable to most readers. Now that Jason has since died and been resurrected as a badass Anti-Hero with his own series, hearing Batman angsting about his death can cause some eye-rolling.
Divorced from its Cold War context, Superman fighting the Viet Cong can seem very silly and on the nose to modern day readers.
The general idea of a book that showed the definitive end of a superhero as iconic as Batman alongside the deaths of important characters such as Joker and Alfred seemed like a shock and departure from the status quo. Since then, an onslaught of Else Worlds stories where anything can happen has dulled this effect for modern day readers.
The fanbase likes to debate over whether or not the edit to the hostage scene was justifiable (edited to where Batman disarms his opponent as opposed to shooting her dead). Supporters argue that it 'fixes' Batman's character, detractors argue that it bowdlerizes the scene, doesn't fit Frank Miller's characterization of Batman and dilutes the effectiveness of his Bond One-Liner. Even more, some people don't realize that Word of God stated Batman didn't kill that Mutant in the comic despite being a shoulder shot with a really big gun.
The breakage got even wider on the release of the second part. Opinions go from Even Better Sequel, okay, an inferior, to a horrible film compared to the first part. And let's not get the flak it gets for how Superman is portrayed, as well as the Cold War era propaganda and Ronald Reagan's portrayal.
Complete Monster: The Joker, after having gone into unresponsive catatonia for a decade, returns to his old habits after the return of Batman to Gotham. Joker begins his rampage by cutting the throat of his therapist and proceeding to fatally gas the entirety of a talk show audience with his Joker toxins, causing them to die a slow death as they laugh themselves to death. To goad Batman into coming after him, Joker continues his rampage into an amusement park, commanding one of his robotic dolls to blow itself up in the tracks of a rollercoaster as a distraction, attempting to use a young child as a Human Shield, murdering a cop for his gun, and eventually devolving to randomly shooting innocents in his way while cackling. After Batman snaps his neck and paralyzes him, the Joker tries to pressure Batman into killing him, and when that fails, the Joker defiantly snaps his own neck the rest of the way anyways and dies with a wide smile on his face, intending to frame Batman for his own death, proclaiming he'll meet Batman in Hell. Even in old age, the Joker is still a master of murderous acts meant primarily to amuse himself, and is motivated by his twisted obsession with his eternal arch-rival, dying with pride that he drove Batman off the edge.
Faux Symbolism: The first time in Part 2 when Clark meets with Bruce out horseback riding, an eagle lands on Clark's arm. A few moments later, it takes off and seizes a defenseless mouse in front of Clark's feet.
Harsher in Hindsight: The film expands on Joker's shooting spree in the Tunnel of Love which can be very, very unsettling in the wake of the Aurora shooting (which was done at the screening of another Batman movie with the initials "TDKR".
Regardless of their portrayal as weak and unable to do what is necessary, many of the pundits are absolutely correct when they say Batman is an outlaw and they're not far off the point when they say he must bear some responsibility for groups acting in his name. Also, creating a culture that is both heavily dependent and admiring of a disturbed outlaw with no hesitation in using brutal violence is hardly an idea worth supporting.
Later on, when Gotham is hit by a nuclear EMP, people who are on the streets scavaging/looting/both are suddenly confronted by the Mutants. They start fighting, only for Batman and the Sons of Batman to tie them all up and only let them go if they want to co-operate with each other to protect the city. The one man who objects is portrayed as a whiner, but it's perfectly reasonable to not want to ally yourself with a bloodthirsty gang of murderers and resent being lumped together with them just because you fought to protect yourself.
The Joker's psychiatrist is portrayed as delusional and the film implies he is at least partially responsible for Joker's massacre. While he may be naive, it is hard to fault the Doctor for attempting to reach Joker and help him deal with his psychosis (You know, that thing psychiatrists working with the Criminally insane are supposed to work towards).
One man in the street says that criminals should be reintegrated into society and that people shouldn't enjoy them being beaten to a pulp. He's then portrayed as a hypocrite because he follows this up by saying he himself would never want to live in the city, but that still doesn't make his earlier points incorrect.
The President is an idiot but he is nonetheless correct that Batman still operating after he agreed to end vigilante work does undermine the credibility of the US government. In fairness to Batman, it's implied people had already lost faith in the government at that point and that they only act when it personally benefits them.
The mayor tries to negotiate with the Mutant leader in a jail cell and gets his throat torn out. The deputy mayor goes on TV and says he too is willing to negotiate, despite what happened.
The whole plan to get the Joker a TV appearance.
What Do You Mean, It's Not for Kids?: Parents would have learned from The Dark Knight and the Arkhamgames that just because it's Batman it's not exactly suitable for children. The two part movie is in the running for the most graphic portrayal yet, at times even going further than the original comic. It's also muddled by the fact the films are rated PG-13 — the same as ultra-campy Batman & Robin!— despite enough rampant violence and bloodshed to qualify for an R, especially during the Joker chapter. Confusingly, HBO Family's descriptors tag the movie with "mild violence", and the violence in the films are most certainly anything but.
Harvey Dent has returned to his criminal ways despite years of therapy and facial reconstruction, but it's because he snapped when he saw his fixed face and believes it's completely ruined now, and he wants to die.
Bruce is also an Iron Woobie, since he's still carrying the pain of losing his parents and the burden of his mission on his shoulders, yet he also enjoys doing what he does (a little too much).