At the core of most Spider-Man stories lies simple maxim: With great power comes great responsibility. There are plenty of ways to interpret this idea, and indeed, it has been explored in pretty much every what you can imagine. It's a surprise, then, to see Dan Slott come up with a new way to apply it to a very familiar concept: time travel.
In "Amazing Spider-Man" #678, Grady, one of Peter's colleagues at Horizon Labs, develops a time travel device that allows a person to step one day in the future. When Grady tests it, it works fine -- but when Peter uses it, he finds New York leveled and uninhabited. Upon his return to the present, he and Grady surmise that this is the result of Peter effectively disappearing from the timeline for 24 hours. The subtext? This is what happens if Spider-Man takes a day off.
As a result of Peter's trip to the future, Grady and Spidey work together to save the city from destruction, co-ordinating rescue efforts with nothing but a newspaper and stopped watch from tomorrow to guide them. Slott sets the issue up perfectly, beginning with an extended sequence of Peter's journey to work across the city. We can all agree that the destruction of New York is A Bad Thing, but the city's significance in the Marvel universe is such that it has become a sort of shorthand for "lots at stake." Slott doesn't use the device lightly, taking care to illustrate on a small scale the people who would be affected by such a catastrophe.
Throughout the story, the mystery of what's coming is as compelling as the character interactions. The appearance of a familiar (though not traditionally Spider-Man-oriented) villain towards the end of the issue doesn't seem enough to justify such impending destruction. If it isn't a fake-out, it's going to require some clever writing to make the situation work. Time travel stories often rely on this sort of twist, so it's doubtless that Slott has something planned, and if so, it's to his credit that it isn't obvious.
One of Slott's more interesting sequences involves Madame Web. The future is her domain, after all, so it makes sense to have her appear in the story. Slott entertainingly subverts her usual dark-and-mysterious tropes, remaining true to the character, but providing some levity to the story despite what's at stake. Obviously, all of New York isn't going to blow up randomly in one issue of Spider-Man, but having the characters believe it to be possible while the readers don't means Slott is free to treat the story as a simple race against time, rather than confront the logic of the situation. Of course Peter and Grady will succeed -- the interesting question is in the "How?"
Artist Humberto Ramos' return to the book brings a lot of the aforementioned energy to story's opening chapter. Even when Ramos' characters are standing still, there's motion and energy in their posture and gesticulations. His style itself may not be to everyone's tastes, but there's no argument that he puts a lot of care and thought into everything he draws.
While it's unlikely neither Ramos art nor Slott's writing on this issue is going to win over any nay-sayers, if you've enjoyed their work so far, this is as good as anything they've done on "Amazing Spider-Man," with an ending that guarantees you'll be there for the next issue.