I own one.
You need to tell us, how do you plan to carry the Z Ultra ? Where are you going to use it ? On the move, on train or in a bus?
Screen cracking issue isn't like the screen cracks all of a sudden, but rather, the double sided glass is, for obvious reasons, fragile as anything, and not recommended for robust use.
Also, the screen is a battery hog, watching videos would have been a better experience if not for the rapidly declining battery level.
No complaints about the performance of the device though, UI is slickkkkkk, and the looks, OMG types.