Its Good but at some points I am not satisfied with its performance.
Good points:
Screen is good, sound is good, battery is good, internal storage is good, camera is good, HD video display is good.
Very user friendly.
Bad Points:
It gets hang. Need to restart again and again.
No Volte is the second bad thing in the ZUK1.
WIFI gets automatically connect and disconnect.
it heats up a lot while playing videos.