Technology cannot cure misuse
Even my iPhone 3G still gets 2 days of standby on its original battery and my iPhone 4 gives me at least 3 days of average use (not counting the Mophie battery case which effectively doubles that.). Of course, I don't leave the thing plugged in 24 hours a day or run the thing 'til the battery is totally dead. Maybe that's why my batteries last so much longer than yours.