Samsung Z1 is a worst product introduced by well known and reputed company samsung.
Samsung Z1 comes with TIZEN OS v2.3 which is also user friendly OS but not very popular.
It comes with 4 inch TFT screen. The Quality of screen is not so good. It have resolution of 480×800. Rear camera of 3.15mp and front camera of 0.3mp.
The worst part in the whole manufacturing of this mobile is battery. Its only 1500mah. Which not at all sufficient for android phones.