I think the main problem was that the character appeared a lot more menacing when he wasn't wearing the costume. If the filmmakers had designed the costume so that it responded to his facial movement, it might have worked a lot better. I also would have preferred a more goofy, psychopathic voice for the character, similar to the Joker, but the voice used in the movie was fine.
I kind of wish that dialogue had actually been in the film. As good as the trilogy was, one thing sorely lacking was a huge collection of Spidey quips.