My 4S is a year old now. I don't know if it's cause of the updates, or the age but battery life definitely isn't the same anymore. It's not drastic though. I've just started charging the thing more often now. I used to not charge it more than once in a day (overnight or morning). Now, I don't mind plugging it in halfway through the day.
I've held the iPhone 5 a few times now and its amazing how light the the thing is. But, I wish Apple would've kept the same thickness of the 4/4S and just increased the size of the battery.
Think of it like this. Apple releases the next iPhone. Marketing the fact that it's thinner, or marketing that it has a larger and longer lasting battery. Which one would get more attention?
Phone's are thin enough. Batteries? Don't last long enough.
But back to your post, just charge the thing up when necessary and give up trying to make it last all day cause I don't really think it's gonna do much for you. That's the way I think of it at least.
