It maybe 'poor' in comparison to a normal phone but when you consider what you can do on the iPhone and what it actually is then it's not too bad.
It is like any device that relies on battery power, if you use it intensively then it will run out quick.
Mine only seems to run out fast if I rinse Tower Madness
Just learn to keep a charger handy and have one in your car. There is a car charger that has a little extra battery kit that you can carry around as back up which is cool.
I have my brightness very low and it's not too bad to look at or battery wise.