And the battery time ov iPhone is very low as well...
Well depends on your usage. If you're running apps , listening to music , watching videos , and of course making calls , sending texts , then you'll be lucky for the battery to last the whole day.
To save battery life :
Make sure wi fi is off when you don't need it. (also where it says "Ask to join networks" in the wi fi menu , that should be On.
Set the screen brightness down.
Turn bluetooth off when you dont need it.
Turn off the equalizer (EQ) in the ipod function.
Turn push notifications off.
Or alternatively don't use the phone at all. 