While the new UI is the most noticeable aspect of iOS 7 there are some other notable improvements under the hood. Many of these involve problems with security in the previous version of iOS. According to this article from zdnet there were a total of 80 bug fixes. Here are a few issues that the bugs could potentially allow.
- Malicious code execution
- Determination of the user’s passcode by an app
- The ability to persist malicious code execution across reboots
- background applications could inject user interface events into the foreground application
- The ability to intercept data protected with IPSec Hybrid Auth
- A person with physical access to the device may be able to bypass the screen lock
- Sandboxed apps could send tweets without user interaction or permission
- Malicious apps could interfere with or control telephony functionality
http://www.zdnet.com/ios-7-patches-80-vulnerabilities-7000020873/