Be aware of BOOT LOOP problem in iOS 8.X JAILBREAK !!!
Make sure you turn off your passcode and Touch ID before you reboot your iDevices After you installed any tweaks from Cydia, because some tweaks might get your iDevices into BOOT LOOP state which is cannot be bypassed by reboot + holding your volume button IF YOU LEFT YOUR PASSCODE AND TOUCH ID ON.
So again for those of you who love to tweak your iPhone with the current jailbreak PP Jailbreak, you should turn off your passcode and Touch ID everytime you reboot your iDevices.