I have an iPhone 4S too, and I'm waiting for the next iPhone. I was tempted to upgrade last year to a 5s, but I personally just don't see what's worth it yet. The jump from 3.5" to 4.0" isn't so big, while the camera is much better on the 5s, the 4S still takes great 8-megapixel shots and 1080p video recording, and in terms of speed, the 4S is still quite speedy, especially on iOS 7.1. While the 5s does benefit from a big speed upgrade, the difference between the 4S and 5s are still relatively marginal (you can wait 2 more seconds to open your mail

) and the 4S is still very capable of running games too. I would love to experience Touch ID, but I wouldn't get the phone just for this feature.
The 4S never had good battery to start with, and yes, my 4S battery has aged too. Recently, it would barely get a day on juice, and if I played a few games, I would charge it twice a day. In the past few weeks, I decided to just keep my iPhone charged wherever I go. Keep it charged at home, charged in the car, charged at the office, so when I go out some place, I know I got enough juice.
Trust me, you'll want to wait. The next iPhone will surely have a bigger display with higher resolution, it'll have an A8 chip with hopefully more than 1GB

and of course they'll update the camera. I'm hoping for new features we still can't think of

The next iPhone will also include a bigger battery, so probably better life than previous iPhones. With the whole rumormill around the next iPhone, I bet this will be one of the biggest jumps in the iPhone's timeline.
It'll probably arrive around end of summer, early fall. We can wait
