As I said, most days it's not bad at all and well within what I would call 'normal' battery drain. I have done the recalibration a few times to no avail. Battery usage has only been erratic on iOS 7. I ran the beta for awhile in the summer, then back to iOS 6 and it was fine on 6. Updated to 7 GM and back to crap. The phone was bought brand new in February and my usage/charging habits haven't changed.
I love almost everything about iOS 7, except for this issue.
just because it was fine before doesn't mean that your phone's battery wasn't deteriorating
It was the same for my phone, it was perfectly fine until one day when it just suddenly decided to die on me and turn off before it reached 0%. Since that day, for the next 2 days, it kept doing that.
I went into the apple store and their diagnostic tests showed that my phone's battery capacity was well under 40% of its original capacity
This happened about 2-3 weeks ago