After years of having an iPhone 4s the battery just starts to go, of course. My original battery only ended up lasting for an hour before it died. This was going to be my trial run before I attempt to fix the volume buttons and the sleep button which are faulty as well. It went so much better than expected, it only took me ten minutes, I was quite impressed. The kit I got had the liberation kit as well so I can fix anything else if need be without messing with those pentalobular screws!
It went great! I was suprised and my phone is like new!
If you're worried about breaking the logic board when lifting the battery, just use the tool around the sides. Take your time.