Will iOS 6 apps run in iOS 7 after upgrade, if so how it will look like?

Hello everyone, recently I upgrade my iPhone 4s to latest iOS 7 beta 6. And I had doubt can we run current  iOS 6 apps in iOS 7 phone? How it will look, will it look like new UI/look (background with blue system icons)? And I had discussion to my friends (Ramki and Krish) about this. They told me to try to install current iOS 6 app in you latest iOS 7 phone and see. We think it will  work as it is and same like iOS 6.

iOS 6 app in iOS7 in iPhone 4s Titanium app

iOS 6 app in iOS7 in iPhone 4s Titanium app

So, I tried with “Titanium kitchen sink”, I build this app with iOS SDK 6.1 and installed (.ipa) using iTunes. You can see the above screen shots. I am running the this app in iOS 7 but still it looks like as it is in iOS 6. So, we had little more time to develop iOS 7 specific app. Even I downloaded apps from app store which are already developed with iOS 6 SDK. Those apps also look like iOS 6 apps in iOS 7.

And also I have another tip for you, if you want to try same thing in iOS 7 simulator :

Try to build and run your app in iOS 6 simulator and then copy the app folder from iOS 6 simulator folder to iOS 7 simulator folder. Open iOS 7 simulator and check with your app. Hopefully, you can open your app without any problem. if so, you can see your app with same iOS6 look in iOS 7 simulator.