The scene with Peter, Gwen, and Uncle Ben in the school hallway was decently acted, and Martin Sheen as Uncle Ben came off well, particularly his mildly amusing "I'm his parole officer" bit. At the same time, I felt that Andrew Garfield and Emma Stone were laying on the whole "awkward and nervous teenagers attracted to one another" a bit thick. Sure, a teenage boy asking out a teenage girl would be full of hesitant pauses, incomplete sentences, and "you know's" but the way it was played here didn't seem as natural.
And something finally dawned on me about the whole "Spidey confronting the carjacker" scene. The apparent sequence of events goes something like this: Carjacker breaks into car. Carjacker gets startled by Spider-Man in the car. Carjacker somehow manages to escape from the car. Spidey chases down and tackles Carjacker. Carjacker pulls a knife on Spidey who feigns that he's scared. Spidey webs up Carjacker to the wall and continues to web Carjacker to wall. Motorcycle cop arrives to deal with Spidey, who dodges his bullets and gets away. And my concern is not only will this be the only scene in which we see Spidey characteristically cracking wise, but that the beats of the scene will feel too long, to the point where Spidey will come off looking more like a jerk to the point the audience will start losing sympathy for him. Granted, we'll wait and see how the scene in question actually plays out, but that's my concern. Not to mention it still doesn't answer the question if the Carjacker had to use an electronic keypad to break into the car, how did Spidey get into the car in the first place? And how did he know which car the carjacker was going to break into?
Also, the additional line Peter says during the dinner table scene where he says "I think [Spider-Man] is just like you [Captain Stacy]...that he's protecting the innocent" once again brings back my misgivings that the film apparently making Peter, as Spider-Man, be a costumed vigilante BEFORE his Uncle Ben gets killed. Again, Peter's motive for fighting crime was because he believes he could have used his powers to prevent his Uncle Ben's murder when he had the chance, thus learning that "with great power comes great responsibility." But if he's already fighting crime and protecting innocent lives before his Uncle Ben is murdered, then, regardless of his motives, Peter is already using his "great powers" in a "responsible" way, thus minimizing the tragic lesson he learns and the moral lesson at the heart of Spider-Man, IMO.
Finally, I agree with the observation that Gwen telling Peter her fear about her father potentially being killed in the line of duty is obvious foreshadowing for Captain Stacy's apparent death and that Gwen is going to blame Peter for failing to protect her father. Makes sense, I suppose.