There’s the happy return of Quidditch, actually seeing relevant classwork, and bringing us into the popularity race as cliques of teens jockey for social position. However, the movie spends much more time and energy ramping up the romance that has been building for the young wizards and witches over the last couple films.
These scenes are added back in masterfully with great care to the audio and video editing. The subplots with Malfoy and the Half-Blood Prince are clearer, as is the horcrux setup and development of young Tom Riddle. The deleted scenes added back in here do much to fix these issues. When I first watched this in the theater, the significance of a lot of these events wasn’t apparent and the overall plot with Draco Malfoy wasn’t very clear (what was all the ‘cabinet training’ about?) Also, for a film ostensibly about the Half-Blood Prince, it really doesn’t seem to be about him at all on first watch (and readers of the novels would’ve been positively livid at all the omissions.) This heralds the ramp up to the final events of the whole series, and this film is essentially setting up for that, with Dumbledore going on the offensive against Voldemort, and trying to put others into position for this. The film starts with the aftermath of the climactic showdown between Voldermort and Dumbledore from OotP and reminds you that Harry has been newly re-orphaned, this time able to experience it as a young adult. I’d attribute this to two main factors: that OotP was the sole HP film written by Michael Goldenberg, and also that several of the performances in this film get very campy at times, which is completely at odds with the overall darkening tone and serious plot of the movie. Re-watching after having seen the whole series, it fares better, though it’s still disappointing. Coming into this film after my favorite in the series, The Order of the Phoenix, I was massively disappointed when I first watched it in the cinema.