Hello freinds this is my honest opinion of using nubia z9 mini for 10 days.
lets start
Design and Build Quality, Display
Design its looks great and have pretty solid built but the cover is plastic and non scratch resistant. you need to b carefull.
Display is stunning, sharp vivid and bright and great viewing angle.
Cameras
camera is really wonderful, not much to complaints. flash sync is not optimised. image quality is great and you have full manual control which is very useful.
however I am not impressed with lowlight video recording as shutter speed is slow and video looks jerky and not smooth at all.
front camera is outstanding for selfie. both cameras are sony sensor which is really really amazing.
NOTE - Since now I have installed V3.67 of nubia rom. which is international version and video recording jolly issue have been resolved.
hardware and software and performance
it packs pretty decent hardware for the price. but optimization is not at all great which is major flaw in this phone. and I am not happy at all. however software UI is pretty easy to use and have lot of useful feature and less clutter. themes looks extremely beautiful and supports its hardware design. Performance is not good. I feel that because of not optimised software and zte has not release any software update since may 2015 for indian variant. however its release many update for chines and international variant.
Sound Quality
Speaker is loud and clear. Call quality is great too. no issue. Network reception is good.
Battery
Non User replaceable 2900 mah battery surprisingly perform really well. fur FullHD display. as I was not expected good battery life. but result was surprisingly better.
Conclusion
I bought this phone for rupees 8600 on quikr brand new. and not happy with software but too happy with camera . looking forward for software update.
this devcie is not recommended for every one. people who can really do software tricks, installing custom rom and however wants good camera they can look at this device.
NOTE - If you bought this phone then you can try international rom for Nubia z9 mini which is v3.67 . I must say above mention most of the issue have been solved. performance is much better everything works great as expected from snapdragon 615. plus no bugs. except for one issue data is not working, which you can fix it solution is available on XDA developers