You can see which emails your individual subscribers have seen, and the actions they've taken with those emails. This is in addition to all the general statistics you can see about the campaign, and mailings, in aggregate.
In your Subscribers area, click on the email address you want to explore.
Click on the Emails Received tab to see which emails have been sent to that specific subscriber, and when the mailing was received.
Click on the large link (Subject Line), to view the specific stats, for just that single mailing.
Click on the smaller link (Campaign Title), to look at the overall stats display for all mailings of that campaign.
The most recent status of the individual email is indicated by one of the mailing status symbols on the right. Click there to expand the details of all the actions that have happened on that individual email, for this specific subscriber. You'll be able to see the action the subscriber took, and the timestamp for when that action happened.