I had a battery drain issue with my Wffe's iPhone, that I actually posted about early in this thread. Perhaps my experience will help you. In my humble opinion, the iOS5 update was an issue, however, since our iPhone was getting a little old and battery life wasn't what it should have been, we sent in the phone to have the battery replaced. Apple, to save time, sent out a different phone. Unfortunately that replacement phone was defective and we had to send that one back. The next one they sent was a winner. Now this process took a month, so by the time we got the replacement phone, the latest update to iOS5 was out. Since the replacement phone had an older OS on it, I proceeded to upgrade to the latest OS. After the upgrade was complete, I SLOWLY went through the set up process on the handset, makeing sure that everything I could turn off was off. I did that based on all the information I read here. My wife only turns on a service when she wants to use it. Since then, battery life has been excellent (for a smart phone)
Now I personally use another phone, not because of any problems with the iPhone, but because the iPhone, like most every other smartphone on the market regardless of the operating system is a computer first, phone second. I am frequently in rural areas where I need a phone that is a phone first and has the ability to connect to more distant towers. In my opinion, the iPhone, along with most other "smart phones" are "city slicker" phones. Often the group of people I am frequently with in those rural areas with a smart phone have to borrow mine to make a call as they do not connect as well. Now I do use a smart phone, but I also carry a back up military grade phone so all I have to do is swap the sim chip to use the phone that connects better.
Why am I telling you all this? I think you are expecting you iPhone to be all things to all people. when you use it that way, it uses up the battery. You have to know that regardless of brand of smart phone, when you use the apps a lot, let things run in the background, multitask, surf and play games endlessly, then the battery will drain quickly. Battery science has not kept up with what we are asking these marvelous little computers to do and in my opinion, in terms of bettery life, no brand has an advantage. It's all in how you use it.
So check your settings, check for a misbehaving app and check your useage habits. You will find the answer there.