Is my iPhone 4S battery life good?

At 18% with minimal use, (in my pocket 1/2 of the time)

Usage: 3 hours 15 minutes
Standby: 10 hours

Literally in ten minutes it went from 38% to 29% while on the Internet

NOPW

Well it depends if you have a lot of apps then expect your battery to drain quickly. What you can try to do to save battery life is by turning screen light a little lower and closing all the apps properly. If you don't know how this can help http://billcrosby.com/mobile-web/iphone/how-to-close-background-applications-on-your-iphone-4/