One feature that most people are going to love in iOS 7 is they no longer have to install updates manually. Thats right iOS 7 will automatically install new App updates when you are connected wifi. You do need to turn the setting on as it is off by default.
To turn it on. Tap settings --> App Store ---> Automatic Updates and flip the switch. Thats it!
Some other things you should also know is that not every app will be updated on Day 1. Apple has a backlog of updates from developers to work through. Another thing is because of the complete overhaul that each and every developer must do to their apps some apps are going to be considered new versions. What this means is that the new app will be a new download and if the app costs money then you will need to pay for it again. Keep in mind that these are almost entirely rewritten with new features and take full advantage of the new OS.