Anyone own either of these phones that can comment on battery life?

I've recently received this phone (W715) and the battery life seems awfull. I left the phone on last night on 83%, it had been charged the night before, this morning it was on 43% and it hadn't been used except for the alarm. I'm not in the best signal area but it does have a constant reception and my Sony K750i sat in the same place every night and would regularily give me 3+ days standby. This is the first phone i've owned in ages where i'm worried it will die on me while i'm out and about.

Manufacturers figures:

Talktime: 4 hours (3G) - 10 hours (2G)
Battery standby: 350 hours (3G) - 400 hours (2G)

This is the first 3G phone i've had am I missing something, i've double checked and the Wi-Fi feature is turned off as i suspected that was running the battery down, are there any 3G features that are known to kill battery life?

Cheers.