Just an ordinary battery replacement in my iPhone 3Gs
20 - 30 minutos
The battery was running out too soon after using the phone for about a year.
The repair went smoothly, your instructions were very clear. It took be about an hour since I was really taking it slow. The only area I was a bit unclear at was removing the #3 ribbon cable between the iPhone screen and logic board. Only suggestion I could make for this is to provide a before and after photo so the appearance of this connector is more clear.
Even if your eyes are excellent seeing up close, I would suggest using a pair of reading glasses, you know the kind you get from the drugstore. Those plus some extra light really makes seeing this small electronics stuff more clear.