I am using lenovo zuk z1 from last 6 month, the things I found good and bad are below
1) Appearance and look is great almost gives you good feeling when you hold it in your hand
2) Definitely its slippery without back case.
3) Well designed and good Screen Size(5.5)
4) Ram is almost good to play games like nova-3 and heavy race games
5) Heating is an issue if you play long enough continuously
6) Battery V.good
7) Camera quality Front and Back is almost satisfied in this range and now we have some better option also in camera range in this price.
8) Low picture quality in low light
9) in day time and indoor camera just work fine and gives you some good pic.
10) Picture color contrast is great
11) lack of external sd card
12) missing FM
13) Sound output works great with headphone and speaker
14) camera hang sometime
15) No UP GRADE IN ANDROID OR OS AVAILABLE THAT IS MAKING IT OLD AND OLD DAY BY DAY.LENOVO TEAM WAKE UP AND SAVE IT .
16) old os and android
hope these points will help someone have a great time guys