Apple has been released iOS 8.1.2 updated OS to the public. Now you can download this new Apple OS update via iTunes or through Settings > General > Software Updates > Download and Install. Apple specially addresses the issue on purchases ringtones from iTunes store. Now you can install iOS 8.1.2 updated version with those fixes and additions.
You can upgrade your iphone 6 plus, 6, 5s, 5c, 5, 4s, ipad mini, air, mini retina, mini 3, air 2, 4, 3, 2, ipad and ipod touch 5th gen devices with any of above methods. Use iOS 8.1.2 OTA download is the most trusted and most used way to upgrade Apple devices.
Install Cydia on iOS 8.1.2
Taig jailbreak or Pangu download has not updated their iOS 8 jailbreak tools upto taig iOS 8.1.2 jailbreak or pangu 8.1.2 jailbreak yet. So there’s no any other tool for install cydia on new iOS 8 update. You have to wait for a better 8.1.2 jailbreak method for this new update