Yesterday, Apple released iOS 7.1 to the public
. iOS 7.1 closes the evasi0n7 jailbreak, so it's advised that jailbreakers stay far away from iOS 7.1
On the other hand, if you're using the iPhone 4, Apple's oldest device that can still run the latest version of Apple's iOS 7 firmware, then iOS 7.1 might be a worthy upgrade. In the release notes for iOS 7.1, Apple noted that the update included "performance improvements for iPhone 4,"