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.
YMMV: Superman: Doomsday
Adaptation Distillation: The story works out well, considering the sheer volume of things that had to be cut to fit the storyline into one movie.
Luthor comes off as a Complete Monster as well. He cures muscular dystrophy, but orders the cure stretched out so it will require lifetime treatments, and abandons an AIDS cure and shoots Mercy, his faithful servant, because she's the only witness to Lex's actions.
Fan Dumb: The crew was told to tell the entire story, The Return Of Superman included. They had about an hour and a half worth of movie to do it in. Therefore, a lot was going to have to be cut or changed in order to fit. Some people were unable to accept that.
Ho Yay: Lex Luthor's obsession raised quite a few eyebrows. His interactions with clone Superman in the red sun room don't help matters.
Nightmare Fuel: Clone Superman walking into a random barber shop and performing brain surgery on himself.
When Clone Superman rescues the cat, you're not sure if he's gonna return the cat to the old lady or kill it in front of her.
Squick: Suspicious of Luthor, Clone Superman casually walks into a beauty parlor and sits at one mirror in what at first is a really bizarre scene. He then uses his x-ray vision to spot the kryptonite encased in lead that Luthor planted in his brain. He then surgically removes it with his heat vision and a pair of scissors. We don't see any of this, but it's no wonder one of the workers fainted.