There are various issues or corn on samsung galaxy s4 which are as follows
1) display is good enough the screen size of display is too small to watch movie or olay big games such as asphalt or gta san andreas
2) sound quality is preety good as samsung does not have very hight volume on it handset it just heareable but sometime incoming call ring are not upto the matk
3) design of phone is good as it is easy to use in one hand but quality is not upto mark as the side as are made up of plastic which is not good to feel
4) the is sometime not very convient to use as there are various function which are not necessary or not in use in day to day life
5) price of the phone is very hight as compare to its features and not worth it
6) worst bettery life