I have been using samsung galaxy s4 since 4 years and I have never faced any problem with the phone, except for it's battery life. It is convenient to use plus you have all the features in one phone. Camera is amazing with 13mp rear and 5mp front camera.
The phone never hangs and processor is optimally fast. You can add external memory card. Touch is superamazing. Durability of the phone is really very nice. It gives amazing features at a fair and affordable price.