I have to admit that I'm not a huge user of Notification Center, and this applies to both iOS and the Mac. One of the reasons that I'm turned off by Notification Center is the disarray that I see when viewing it.
By default, Notification Center is set to sort manually, which means that you can go into its preferences, and sort each app by hand. That's fine and all, but it makes for a less than ideal experience when trying to find the most relevant notifications based on time of arrival.
For me, this results in a less than ideal experience when opening Notification Center. If you have a lot of apps enabled for Notifications, it can be overwhelming, because there's no real logical order to the way they're sorted. To remedy this issue, try this simple tip, and sort your notifications by time of arrival instead.