Well I finished watching Spider-Man 3 last night, and I'm sorry to say that there are multiple problems with it aside from Venom.
First, the whole film just doesn't have the same feel/charm as the first two. It starts out good and you expect that it will be like the first two, but it isn't. Second, compared to her role in the previous films, Mary Jane's character seems a lot more self-centered. Third, after two films, they expect us to believe that Flint Marco was actually responsible for killing Uncle Ben. It's one of those common "you thought this was true from the beginning but it isn't" stories that often appear in trilogies. I won't even bother talking about Topher Grace's Eddie Brock/Venom because you all know darn well why he wasn't well received.
Spider-Man 3 is one of those movies where when I'm watching it I ask myself "Am I being too hard on it? Is this actually an OK superhero movie?" However, when left to think about it, I can't help but feel that it was a massive waste of potential. 3 out of 5 stars.