On the two iPhones I use the most, I have seriously great battery life consistently.
On one:
4 days 10 hours standby
8 hours usage
iPhone was not plugged in since last charge
WiFi and bluetooth off, email on and checking every 30 minutes.
Second iPhone currently at:
1 day 20 hours standby
3 hours 10 minutes usage
Wifi off, bluetooth on, email off
Battery shows just under full
iPhone was not plugged in since last charge