Apple has released iOS 8.1.3 this morning, after weeks of extensive testing. The release notes say that the update includes increased stability and performance improvements, as well as various major bug fixes. It also reduces the amount of storage required to perform updates.
You can access the new firmware over the air via Settings > General > Software Update, or via iTunes by connecting your iPhone, iPad or iPod touch to a computer. But as usual, we recommend that users who are jailbroken, or plan to jailbreak, avoid the update for now.