To be brutally honest, I feel the movie showed a mash-up of important scenes, leaving out the extra background information by substituting it with fun montages. I loved to see Jo and Hero's chemistry working out fantastically, but without the link between scenes, the movie feels absolutely rushed. Only people who've read the Wattpad/book series would understand what's going on.
Nonetheless, the objective of delivering the plot twist was spot on but of course, hopefully in the sequel, there will be a better flow of the story, rather than rushed intense scenes. There's also not much work on character development in the film, which I think should be emphasized on to make Anna Todd's brain-baby beautifully alive in colour.
Other than that, I loved the movie--it's a book-fan thing.