iOS 8.1.1 update is available to download, you can install this update OTA or direct download links IPSW files are available below to use with iTunes. iPhone 4S and iPad 2 will get performance improvements from this update, in addition to stability and boost in performance for specific devices there are different bugs fixed in this update. This is final version of iOS 8.1.1 build 12B435.
Install iOS 8.1.1 OTA
You can update your device OTA (over-the-air) from iPhone, iPad or iPod Touch. Go to Settings > General > Software update menu. OTA update size of the is vary from device to device, from 64MB to around 200MB. But make sure you have good internet connection and connect device to power source or charge device battery more than 50%.
If you want to update iOS 8.1.1 with iTunes you can download iPSW firmware files below for your iPhone, iPad, or iPod Touch device.
Direct Download Links
iOS 8.1.1 for iPhone
iOS 8.1.1 for iPad
iOS 8.1.1 for iPod Touch
iPod touch 5th gen