Every director thinks that every actor can pull a Robert Downey Jr. It happened in Green Lantern and I wouldn't be surprised if it happened again.
In all honesty Garfield isn't the problem. I can't help but focus on the negative right now due to frustration, but he and Stone have never been better together. I actually appreciate her more in this film than the last, as one of my biggest beefs with the first movie is that she was something of a blank slate, and was little more than Peter's sounding board for his exposition and monologues. She's actually given a character this time.
Every other character, on the other hand? Hollow, unexplored, campy, cliched, shallow, you name it.
Speaking of characters, I'm actually quite taken aback by how devoid this movie is of them. One thing I recall about the Raimi films, and I really couldn't care less who this comparison inevitably pisses off, is that Spidey's world seemed so full of life; New York was just teeming with so many personalities that Peter and the characters in those movies interacted with. This movie is overwhelmingly Peter & Gwen's little back-and-forth. It's cute when they're together, but it never goes
anywhere and manages to drag for the entire duration of the movie. The big payoff at the end is the only reason for it, mind you, all of which could have been avoided if their relationship (as well as her as a character) was properly and thoroughly developed in the previous movie. The plot just drags and drags...and
drags.
There's even some ridiculously unnecessary bit about a couple of airplanes. Talk about fodder...