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.
I Am Not Shazam: Many people call Frankenstein's Monster "Frankenstein", while he actually has no name. "Frankenstein" is the name of his maker, Victor Frankenstein. But we can probably blame Mary Shelley for that; it would be a lot clearer to all if she'd called her novel "Doctor Frankenstein". This confusion dates back nearly as far as the novel itself, and became established during periods when the actual book was out of print, but its characters and plot were being emulated by stage plays, knockoffs and parodies throughout the pre-copyright 19th century.
Either Victor Frankenstein is a tragic and naive scientist who - in his enthusiasm - bit more off than he could chew and paid a horrible price and suffered too much for it and has every right to be emo about it OR selfish asshole who tried to keep his PR clean by abandoning the monster and got what was coming to him and he's being whiny about it.
And the monster is either a far bigger woobie than Vic could ever hope to be, abandoned by the only person he could possibly consider a parent, or a wangsty monster with a Freudian Excuse who needs to take responsibility for his actions?
Ho Yay: Victor's describes Henry Clerval in a way someone would describe their love interest. Heck, his description of Henry is more thorough than those of his fiancée, Elizabeth. And he reacts to Henry's murder more strongly than Elizabeth's murder, too!
It Gets Better: The first few chapters detail the back story of the sea captain who met the titular Doctor on his expedition to find the North Pole. If you didn't know that the novel was a Story Within a Story (Within a Story) you would read the opening thinking "Get to the unholy abominations against nature, already!"
There's a long segment where the Monster watches a family for about a year - his yearning for a mate comes from the young man being betrothed to an older woman from some exotic place, as well as his identification with Adam's desire for a mate in Milton's Paradise Lost.
Too Dumb to Live: Vic runs away from his successful experiment in creating life because it's ugly. Then he destroys the Bride he was making for it, causing the Creature to go on a rampage. All the Creature wanted was some familial love, and then a female companion. C'mere, Vic... we need to slap some of the stupid out of you. In fairness, he destroyed the mate for fear that, unlike his first creation, it would be a monster in manner as well as looks.
He's also worried that the two creations together could breed and create a race of monsters. Um... brilliant biologist and anatomist hasn't heard of tying tubes?
Tubal ligations and vasectomies weren't viable with humans until the late 1800s. Castration would still be on the table...
When the monster told Victor that he "would be with you on your wedding night" he took that to mean that the monster planned to kill him then, even though its modus operandi up to that point had been to target his loved ones. He prepares to confront the monster alone while leaving his new wife undefended; the monster kills her instead.
I Am Not Shazam: The name of the hunchbacked assistant is not Igor, it's Fritz. Ygor is an unrelated character from the third and fourth movies, who had a broken neck and didn't really assist the Doctor (he's the main antagonist in fact).