iPhone 4 battery installation was much quicker than I imagined
5 - 30 minutos
My original battery was 21 months old. It still worked fairly well, but I could tell it wasn't holding charge like it used to. Sometimes it would require recharging by late afternoon after starting the day at 100%.
Repair was easy... just followed the steps. Only issue I encountered was the blue "spudger" tip broke as I was gently prying the old battery out. Not as sturdy as it should be. I was still able to use it anyway.
Don't sweat this repair. It's quite easy!