Apple is always trying to make better things to their existing customers. iOS 8.1.1 is a good example for that, because they mainly focus on this iOS 8.1.1 update to improve performance on older iOS devices such as iPhone 4S and iPad 2. From installing this iOS 8.1.1 update you can feel iOS experience faster than previous iOS 8 updates.
If you are using an Jailbroken iOS device, stay away from this update for few dates. Because iOS 8.1.1 Jailbreak still not available.
iOS 8.1.1 also compatible with all iOS 8 supported iOS devices such as iPhone 6 plus/ iPhone 6 / iPhone 5S / iPhone 5C / iPhone 5 / iPhone 4S / iPad mini models / iPad Air models / iPad 4 / iPad 3 / iPad 2 and iPod touch 5G.
You can download iOS 8.1.1 by Over The Air by going to Settings > General > Software Update
also you can watch our previous tutorials for Jailbreak iOS 8.1