I ordered the replacement battery because my phone has gotten slower and slower when opening apps. Recent news stories about Apple deliberately slowing phones down to help battery life. So I decided to replace it to see what would happen.
The repair was very simple. I was able to get the old battery out just using the plastic strap and did not have to use the pry tools except where the battery plugs into the phone. You do need to be very careful when removing the battery plug. The ground contact will come loose and will need to be positioned correctly when re-assembling. I also had the camera lens cover fall from the back after sliding it off.
The replacement procedure supplied by i-fix it is very good but I also recommend that you go to You Tube and watch a video of the replacement. There are some very good ones that spend time talking about the small contact bracket that has to be re-positioned. I also recommend that you place a white towel under the phone to catch anything that may get dropped.