Think hard about this people. I'm sure Apple did a poll SOMEWHERE to say that people want thinner phones. Must've been at a party that's priced higher than the cost of my house as those are the only people who I would guess would rather have a thinner phone.
People want a removable battery but seriously, I know of maybe one person who carried a spare. I hear more people having a charger in the car, or at work.
So having a removable battery is not required. And let's face it, battery wearing is not a concern like it was 10-15 years ago. Not to mention WE would all dump the current phone if Apple released a new model a year from now. Even those that say nay, they wait two years b4 buying another iphone, the battery will last that long. It has so far.
I would keep the iphone the same thickness. I would've wanted a .25in to .5in more to the width with the height increase. It'll be still easy to hold and the extra width will come in handy for reading web pages. Trying to read a web page when in landscape is like covering 3/4th of your screen and trying to read what's on the page. And in portrait mode, its just a hair to thin to read small fonts without zooming in a lot.
Those that say, the battery is good. You charge it every day. Yes. You were TRAINED to charge it every day or it'll die. Have you looked at the standby for the 4s? 200 hours. Right. RIGHT.... You shouldn't need to charge every night. So you use internet,camera, apps, etc. Apple knew that. They made the phone. You should at least get 3 days with light use without worrying the phone is at 15% battery.
Now, with the extra size of the iphone, having a larger battery would be perfect. With the increase of width and length at the same thickness, they should be able to go from a 1430mAh to a 3000mAh battery. So it'll be a bit heavier. Beats carrying around a "battery case" And now the phone will last a full day of use, and on light usage, it'll easily last 3 days.