I love the build quality of the phone. To me it's very sexy. But what holds it back is the Sony UI. I have had 2 different brands Android phones (HTC and Samsung). The UI in both brands are more flexible or integrated to some apps.
For example the HTC and Samsung you can link your Facebook profile picture in your personal contact info. But with the XZ you can only link your contacts and can't link your own profile. Also the lockscreen is not fully customizable. You can only change the wallpaper and not the icons. You will need a 3rd party app to be able to change or customize the lockscreen (I think widget locker from Google play store works but not sure). Other than that I love the phone.