This is a very highly anticipated film. Unfortunately, most who have seen it thought it's not as great as they hope it to be. I thought it was decent though. Except that the story may be a 'lil bit too congested. They trying to tell too many things in 1 movie.
The main draw of the Spiderman comic is that despite been a superhero, Spiderman faces the problems of the average student. He faces BGR problems. He struggles to earn enough money to pay for his school fees and rent. And he's just a boy growing up. When he discover he has the powers of a spider, he did not join the superhero profession immediately. Instead, he used it to earn pocket money. It took the death of his uncle Ben, and the famous last line, "With great power comes great responsibilty", to make him see the errors of his ways.
For Spider-man 3 movie, it's similar. After the initial mistrusts of him by the public due to the papers trying to paint him in a bad light, he has now become popular. And that has caused a nerd like him to have a massive boost in ego. His own obsession in his success caused him to be blind to the problems of his girlfriend, Mary Jane. When he told his aunt May that he wants to propose to MJ, she told him that a man has to put his wife above everything, including himself. He said that he can, but he actually didn't.
And when he later came into contact with the alien symbiote, he become worse. He starts getting arrogant and violent. He hurt even more people, including his good friend Harry Osborn.
Harry had hated Spider-man. He believed that he's the one who killed his father, Norman. When he discovers the room where his father kept his equipment for Green Goblin, he took over the mantle of the Green Goblin and seek revenge on Spiderman. Fortunately, he came to know the truth of his father's death and patched up with Peter Parker.
Escape convict, Flint Marco, is the 1 who killed his uncle. He was running away from a burglary and wanted to take uncle Ben's car. He accidentally pressed the trigger of his gun and killed him. He was guilt ridden, but he still need to find enough money to pay for his daughter's operation. While running away from the police, he barges into a science experiment and become the Sandman. With his newfound powers, he resorts to robbery to raise the money and was thwarted by Spiderman numerous times. He finally attain piece of mind when he confesses to Spiderman about his killing uncle Ben and Spiderman forgave him.
And lastly, there's Eddie Brock. He's Peter Parker's rival in photo journalism. When Peter Parker exposes his dishonest deeds to get recognition, he has an axe to grind with Peter Parker. Then, when Peter Parker removes the alien symbiote, it feel to him and he became the venom. He sought to kill Spiderman.
In the 1st Spiderman movie, MJ was Peter Parker's childhood crush, but in the original comic, Peter Parker was with Gwen Stacy. In the 1st movie, MJ was captured by Green Goblin and thrown down from Queensboro Bridge and saved by Spiderman. In the original comic, it's Gwen Stacy who was thrown. But Spiderman did no managed to save her and she died. It was after her death that Peter Parker came to be with MJ. In Spiderman 3, Gwen Stacy become the alternate love interest of Peter Parker, and he uses her to spite MJ.
With so many subplots, it's no wonder most people don't enjoy it. I thought it was ok, though I would wish more focus to be given to Harry Osborn and Venom. I especially like the part where Peter neglects MJ.
1 other thing that I don't like about the movie is that MJ appears frail and seems to be the damsel in distress too many times. Mary Jane is supposed to be a feisty woman and very capable of looking after herself. She is trained in self-defense with teachers including Captain America, and had even saved Spiderman's life a few times.