I'm rewatching Spider-Man 3 right now on Blu-ray and, while I've always liked the movie and feel like it's incredibly underrated, I've come to the realization that I've kind of subconsciously bought into the 'hate' for the film by ranking it below Spider-Man 2 when in fact it surpasses that movie and closes out Raimi's series in phenomenal fashion by doing the following things:
1) It organically builds on the foundation established by Spider-Man and Spider-Man 2 while simultaneously adding new layers to said story by 'flipping the script' in regards to what we thought we knew about his Uncle Ben's death and the circumstances that led Peter Parker to become Spider-Man in the first place.
2) It creates a perfect narrative "circle". By revisiting and building upon narrative elements from the first and second films, Spider-Man 3 allows Sam Raimi the opportunity to bring a sense of narrative closure to the character-driven story arcs he helped bring to life on film while simultaneously "leaving the door open" for future narrative possibilities.
3) It makes the character of Venom interesting without losing focus on Spider-Man. It's been well-documented that Sam Raimi did not want to include the character of Venom in Spider-Man 3 and was forced to by producer Avi Arad, but, in spite of the circumstances surrounding the character's inclusion, he still managed to make him interesting without his presence overshadowing or pulling the film's narrative focus away from its titular hero.
4) It serves as a narrative platform through which Raimi can explore the themes of mirroring' and 'reflection', from Harry's emergence/ascendance as the second Green Goblin mirroring that of his father's to Eddie and Gwen being mirror images of Peter and Mary Jane to Eddie and Harry's respective hatreds of Peter and resultant descents into darkness mirroring each other to even the relationship between Peter and his Aunt May mirroring that of Flint and his daughter Penny.
5) It manifests the psychological effect of the symbiote on Peter in a way that remains consistent with his previously-established characterization. One of the biggest issues I realized that I have with the "black suit"/Venom storyline conceptually is that it's a thin excuse for making Peter take on a completely different and unrecognizable personality just for the sake of doing so, which doesn't realistically make any sense narratively, and it's a pitfall that Raimi thankfully avoided by instead using the symbiote to amplify elements of Peter's personality that were already present in his psychological subconscious.