Hi all, just adding my two cents worth,
5.0.1 seems about the same as 5.0 for me. I did do a rest all settings after getting the phone and I think I'm getting pretty close to what Apple says usage will be.
With most of the time on wifi apart from about 5 hours on 3g here's what I've done - a number of short calls, half a dozen text messages sent and received, read and received about a dozen emails, location based reminders current for about 3 hours, around 2 hours online and using twitter and Facebook, played games for about half an hour, and about half an hour playing with settings and Siri - my usage is:
Standby time = 1 day, 12 hours
Usage time = 4 hours, 50 minutes
Battery left = 39%
FYI
My seetings are:
Mail: iCloud and Gmail accounts both set to 15 minute fetch
iCloud: mail, reminders, contacts, calendars, notes, documents, photo stream
Notifications: phone, messages, reminders, calendar, cnbc, mail, twitter, find friends
Location: maps, siri, weather, reminders, twitter
Sytem services: all off but Mobile Network Search is on.
Will let you know the final result when battery drains.