Samsung galaxy s4 is just one of the slowest smaetphones I have use.
The processors are good enough but the ram is quite low especially if you are running Samsung's touchwiz Ui.
The screen is good but now you get more better smartphone with good quality screen.
Coming to battery this smartphone has 2600 mAh battery.
Considering the powerful battery consuming CPU and graphics and the HD screen the battery experience is worst.
The built quality of the smartphone is worst.
Full plastic.
Camera is not that great and front camera is just ok.
Overall have a look on another device.