Yes a lot of people are having this issue it's from the ios 6 update. Some users are reporting battery drains a lot after updating their device
There have always been a lot of battery problems posted about in these forums following each and every iOS update. Personally, I believe that the battery really isn't discharging any faster, it is just that the charging circuit is confused and needs to be reset. I always perform a setup as a new phone for major updates, for example iOS3 to iOS4, 4 to 5, 5 to 6, which should be a 'reset' for the charging system, but I do a simple update for point releases--6.0 to 6.0.1, etc. I have never had a problem with battery performance when performing the full update as new, only when I did a 'normal' update for a point release. If I perform an update with a restore from the old backup after a major update the battery problem did appear.
After every iOS point update I always do a full reset--home and on/off buttons held down until the Apple appears--three or four times over the course of a couple of days. I allow the phone to fully charge overnight every night.
This has always resulted in 'normal' battery life after one or a few reset cycles. By 'normal' I mean that a fully charged iPhone, with email and other notifications enabled and set to push, and no particular attention paid to battery conserving techniques, will discharge to about 89% over a 10 hour day. If I make a few phone calls and surf the web a bit then the level has fell to 70% or so, but unless I heavily use my iPhone 5 it doesn't drop below that point.
Prior to performing the resets the charge level would sometimes drop into the 50's or 60's or even lower in a few hours without using the iPhone. This problem 'scenario' has happened with every iPhone I have ever owned and I've owned all but the original iPhone.
As always, YMMV. I make no claims as to its usability for anyone else.