As with other book adaptations, the movie must make some concessions in terms of what to keep and what to discard. This movie keeps most of the core and important plot points, enough to make the story coherent and understandable. It does well transitioning the ideas and designs, making you want to see more of this world. Hogwarts is huge and immense, just like it should be but the number of students during the scene in the great hall makes it seem that there are way too less students and the rooms seem smaller than they should. Harry Potter's normal school life gets glimpsed over but the Quidditch match was exciting and fun to watch. It's a shame that they couldn't fit in all of the trials at the end because they were some of the best bits in the film. That said, by that point, the film was over the 2 hour mark and I don't think it would benefit from being even longer. If you have read the book though, there's no surprises, yes, they are changes here and there but it can get a little bit boring when you know what's coming next (this is a common complaint with book adaptations in general). Overall, one of the better and more enjoyable Harry Potter films (the latter films are too hard and complex to understand if you haven't read the source material).