Very nice episode. I liked the slow build and the subtle transition to connect it to 9/11. May not have seemed that way to people not from the city because it just smacked them when the old lady started talking about the view from the office. Anyone familiar with the area probably started getting chills at the first site of the chambers street station.
The whole computer incident was standard Margaret/Linda fare. The Jake subplot seemed irrelevant but did supply a couple of one liners.
It would have been very interesting to see how John would have interacted with his friend's wife.
All and all a very satisfying episode that left me misty towards the end. I, like the others reviewers, do not understand why this was done so late.