10 - 30 minuten
iPhone 4S battery was losing power quickly. I have had my phone for 1 1/2 years and the battery was lasting about 2 -3 hours on a full charge. I also have an AT&T micro-cell in the house that I think drains the battery faster than normal.
Repair took about 10-15 minutes. I was concerned that taking out the old battery would wipe my phone of all information but that was not the case. I did, however, back up all data beforehand. Once the new battery was installed, all data was there. Whew!
Some advise - I put on disposable latex gloves so that I did not leave any oil from my hands on the tiny contacts. I also watched several different videos on how to replace the battery. This was helpful since I could see more detail in other videos. The tiny antennae was the biggest concern but was not shown that prominently in the ifixit video. Plus I had 2 screws on the inside where your video only shows one. I would also have preferred some instructions included with the tools and battery. I would definitely use ifixit again -- made me feel empowered!