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: Harry Potter and the Prisoner of Azkaban
YMMV tropes present in the book:
Alternate Character Interpretation: Sir Cadogan, the portrait that takes over guarding Gryffindor Tower for The Fat Lady after she's attacked by Sirius Black, and whose work style involves setting "ridiculously complicated" passwords, and changing them at least twice a day. Is he stark raving mad, or Properly Paranoid taken Up to Eleven?
Ending Fatigue: Not too bad, but off to see Buckbeak get executed - diverted to shrieking shack, long Plot Dump, Werewolf ensues, time turner, going back though the evening and THEN it's over.
Fridge Brilliance: Why is Snape almost psychotic with rage over Sirius' escape at the end? Because, as far as he knows, Sirius is the one who betrayed the Potters and thus got Lily killed - rather less petty than the childhood grudge everyone assumes (although Snape's holding onto that, too).
Also, Snape asks Lupin if Harry might have gotten the Marauder's Map from one of the makers. Considering he went to school with the Marauders, and was likely insulted by them in the same way as the map (as well as familiar with their nicknames), he probably suspects that Lupin had something to do with the map - which he does.
In the film, the music Lupin plays during the Boggart lesson. Seems silly at first but then you realise he's trying to keep the mood light so the students will be able to imagine their worst fears as something comical.
The first time Ron and Harry notice Hermione has briefly stepped away from them between classes, she changes the subject by voicing her hope that there's something good for lunch, she's starving. Of course she's starving: she's just used the Time Turner to live through twice as many hours since breakfast as they did!
"Funny Aneurysm" Moment: At one point in Harry Potter and the Philosopher's Stone, Scabbers bit Goyle on the knuckle (which was even referenced by Fred and George Weasley in Azkaban). Come Azkaban, and the revelation that Scabbers was actually Peter Pettigrew, who was the true person responsible for leaking Lily and James Potter's location to Lord Voldemort and thus their deaths, not to mention the revelation in Goblet of Fire that Goyle's father was most likely one of Pettigrew's comrades among the Death Eaters. it becomes somewhat disturbing.
Also Ron carrying him around in his pocket and Scabbers even fell asleep on Harry's bed at one point in Philosopher's stone.
Growing the Beard: Many fans believe that this is the turning point for the series as a whole, citing the encounter at the Shrieking Shack as evidence.
One-Scene Wonder: Aunt Marge only appears in one chapter, but still manages to be among the more despicable characters in the series, perhaps even more so than her brother Vernon.
Shipping Goggles: The series has enough of this to fill a page, but this entry probably has the best example, what has been dubbed "The Symbolic Flight". This theory states that because Harry and Hermione flew together on Buckbeak together and without Ron, that they are destined to be together - ignoring the fact that Ron was only not present because he broke his leg earlier.
Strawman Has a Point: Lucuis Malfoy is a pretty awful person, who attempted to assault Harry at the end of last book for freeing Dobby, but is it really difficult to see Hagrid as a Designated Hero for trying to keep Buckbeak at school? In the "Fantastic Beasts and where to find them" book it list Hippogriffs as one of the most dangerous beasts known to wizard kind and Hagrid thought it was appropriate to have thirteen year-olds approach them and train them? Granted Draco screwed up practically on purpose, but what if it was another student being attacked by accident?
It's still pretty difficult: Hagrid flat-out warned everyone "Don't insult a Hippogriff, it may be the last thing you ever do" at the start of the lesson, and makes sure to teach them how to safely approach them, and recognise signs that it's not safe. Also, note how none of the students other than Malfoy are attacked. Presumably Hagrid (or Kettleburn) had trained the Hippogriffs to behave themselves at some point.
YMMV tropes present in the film:
Accidental Innuendo: The scene from the book listed above is even more dodgy in the film, when Harry's Uncle Vernon keeps bursting into the room to find out what's going on. Vernon is played by Richard Griffiths, AKA Uncle Monty.
Big Lipped Alligator Moment: After everyone arrives at Hogwarts to start the new year, the Fat Lady won't let them into Gryffindor Tower because she's too busy trying to shatter a glass with her voice. That scene has never made any sense. And they left so many important bits out...
The talking shrunken head on the Knight Bus. But Rowling has stated that she finds the shrunken head hilarious and "wishes [she'd] thought of that."
Broken Base: Half the fanbase considers this one of the best (if not the best) Harry Potter film in the franchise, or at least when the Harry Potter films started getting good. The other half considers this movie to be one of the worst (if not the worst) Harry Potter film in the franchise. The film was mostly better received by critics than the first two, although it was the first HP film not to get four stars from Roger Ebert. Also, this is J.K. Rowling's favorite film.
Particular anger was given to Steve Kloves having his favorite character Hermione steal Ron's big moment of declaring Sirius will have to go through them to get to Harry, despite having a broken leg.
Growing the Beard: According to most professional critics, along with about half of the fans. At the very least, people agreed that the younger actors and actresses were finally fitting snugly into their roles (aside from the Narm mentioned below).
Internet Backdraft: Best movie in the series? Worst movie in the series? Middlingest movie in the series? Whatever your opinion, a huge chunk of the Fan Dumb will loathe you for it.
Narm: The movie is full of it, most notably Harry's crying scene in Hogsmeade (blame Daniel Radcliffe), Draco getting attacked by Buckbeak (blame Tom Felton), and the punching scene (blame Emma Watson, Tom Felton, andSteve Kloves).
Apparently "believing in yourself" equates to SHOUTING AT THE TOP OF YOUR LUNGS. No quiet confidence in the film version of the Potterverse. EXPECTO LOUDYELLUM!
Malfoy being attacked by Buckbeak, which was deliberatelyNarm-y; in the book, it was stated that he over-played how bad the injury really was. Why? Because he's Draco Malfoy and he's a whiny brat. And because he wanted to get Hagrid fired.