These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Joker: If you don't like the movie, I've got slides!
Ensemble Darkhorse: The Jokerz in this movienote Bonk, Chucko, Ghoul, Dee Dee, and Woof, especially Dee Dee, are all extremely popular among the fandom. This is likely the reason they were included in the Bad Future episode of Justice League Unlimited.
Foe Yay: One of the biggest examples of Batman/Joker. To put it bluntly, Joker kidnapped one of Batman's "sons" with the intention of molding him into his own "son".
Hilarious in Hindsight: When we find out the Dee-Dee twins are Harleen Quinzel's granddaughters. As we know from the flashback, Harley Quinn basically went along with Joker's plans to kidnap and warp Tim into "Joker Junior" because she couldn't stand the thought of actually carrying & delivering a baby of her own — note the disgust on her face and the sarcasm dripping from her voice when she talks about the "joy of childbirth". And yet she then went on to have at least one kid of her own the normal way...
There IS always adoption...
Her comment on the "joy of childbirth", with the body language, may have meant she looked forward to the idea, but Joker refused to go through with the commitment with a hormonal, pregnant Harley for about 9 months, not to mention the heavy investment for the first several years of the child's development that would require them to lay low for a long time... Joker screwed her out of her chance of finally "getting some". At least, that seems the case until "Arkham City''...
The Joker crashes a high-rise party, and escapes because Batman has to save a guest from falling. Sound familiar?
Inferred Holocaust: On two occasions, Joker uses a gigantic military orbital laser to carve a swathe of destruction through Gotham. Civilian casualties are never mentioned on either occasion, but it's a giant military laser carving through a major city, often going right through buildings. One can only imagine the death toll. The commentary track notes that the laser miraculously avoided hitting a single person. Then again, there are several ways to interpret, 'Didn't hit a SINGLE person...'
Moral Event Horizon: The movie gives the Clown Prince of Crime a rather infamous line-crossing moment: he kidnapped Robin, tortured and mind raped him for three weeks, mutilated him, "fixed" him up as Joker Jr., implanted a microchip doctored with the Joker's DNA into his body, and invited Batman over to see his work in detail (which included a home video of the boy's torture labeled as "Our Family Memories"). He then reveals that he's learned Batman's secret identity, mocks him for it (and for not having the balls to kill him after all this), and knifes him before he tosses "J.J." a spear gun to finish him off with. Also worth mentioning that this particular MEH crossing was the former page picture.
Even Mark Hamill, who had been voicing the Joker for years at this point, felt uncomfortable with the role this time.
Overshadowed By Controversy: The film will forever be remembered for two controversial death scenes (Bonk's and the Joker's), which were first heavily altered along with other scenes before it was released in 2000, in an attempt to tone down the violence due to being pressured by criticism from Moral Guardians and Media Watchdogs for violence in films during the fallout of Columbine; and then eventually brought back in 2002 when the Bowdlerised version didn't help matters but only caused unrest among many Batman fans that lasted for over a year.
The Problem with Licensed Games: The PlayStation and Nintendo 64 versions had bad music, bad graphics, clunky controls and repetitive boring gameplay, which is why it was given lowest scores from GameRankings and Metacritic. The Game Boy Color version fared a little better, however, but some reviews are mixed.
They Wasted a Perfectly Good Plot: The film made it look like the new Joker was Tim Drake, who had finally succumbed to his madness after the torture and brainwashing inflicted by the Joker long ago, and adopted the Joker persona for himself. This would be believable in the context, it would be much more powerful and tragic than the actual story, and it would give the Joker the last laugh from beyond the grave, which would be in keeping with his presentation in the movie up until that point. It would actually have made a pretty good Batman film. Instead, there's a suspension-of-disbelief straining explanation about a mind-control chip and magical DNA. Though one has to wonder if the stated potential idea would have been even possible to get past the censors.....
In the original ending, the Joker actually was Tim Drake, with no microchip involved, but that didn't sit well with the test audience.