It was completely wrong. The hedges did not move, there was no sphinx, acromantula, or Blast-Ended Screwts. There weren't any Blast-Ended Screwts in the movie at all, for that matter. The opponents had to navigate through a maze to get to the Triwizard Cup to win the tournament. This is shown quickly in the movie and the only consistent danger appears to be the collapsing of the walls, yet in the book Harry is forced to use his wit and knowledge of spells to plot his course and face various creatures.
Secondly, Neville did not help Harry discover Gillyweed, Dobby did. Originally, Mad-Eye had intended for Neville to show Harry the book he gave him, which contained a full explanation of Gillyweed. Dobby overheard Moody talking to McGonagall about Gillyweed, and relayed the message to Harry.
Another detail that was changed was at the Quidditch match. Harry, Hermione and the Weasleys were supposed to be in a box with Cornelius Fudge, the Prime Minister from Bulgaria and Ludo Bagman, but instead they were stuck in the nosebleed section. Small bit, with not much importance to it but was messed up nevertheless. Also at the Quidditch match, Winky was blamed for the stealing of Harry's wand, and casting the spell that produced the Dark Mark. Winky was left out of the movie all together, which I thought was