If I can use the phone for a longer period of time why get a new one?
10 - 30 minuten
The phone would die way before reaching 1% battery life. Sometimes, it would die at 20% other times even at 60%. The battery would charge very quickly and die very quickly as well.
The repair was simple. However, I did screw up at one point by dropping one of the screws on the floor. That delayed the process significantly. Also I would recommend taking detailed pictures of everything you take off before you do (if you can borrow someone else's phone while you do the repair) to facilitate the assembling process. In my case there was a particular piece that was not fitting in and after doing a lot of research on line I found out I was putting it facing the wrong way.
Even after changing the battery my phone still died at 20%. I did some research and found out that a lot of people have that kind of problem after upgrading to iOS7. So I backed up the phone and restored it to original settings. Keep in mind that if you restore your phone to the factory settings using iTunes your phone will be upgraded to iOS8 automatically and the iPhone 4S can barely handle iOS7 so imagine how much worse your phone will run with iOS8. Therefore, restore your phone without using iTunes there is a tutorial on line that tells you how. So after doing all of the above my phone runs great again. It feels almost like having a new phone. If you can spend $30 for a new battery why spend $400-800 on a new phone?