Unfortunately, Apple doesn't allow the freedom of rolling back an update.
Basically, their attitude is too bad, soo sad!
Sorry, I am at a point of losing my patience with Apple and their loss of interest in doing what is right for the customers who made them successful.
BTW, I know it is too late to tell you this but the best advice I can give you is to never-ever update the iOS until you have waited two weeks and watched for issue trends in the Apple forums.
There is another way to roll-back but if I told you, my message would get deleted. Just Google iOS rollback.
Shorter battery life was a very common problem with the early versions of iOS 4.
And I have seen a number of complaints of short battery life with iOS 6.00. Just search the forum for recent postings.
These type of complaints follow every single update that has ever been released. Most have no issues.
Just search the forums.