5 - 30 Minuten
Battery was not holding a charge as long as it did originally
Worked as explained in the iFixit video. However the first battery sent was defective. This caused the phone to randomly restart and the charge percentage was not consistent. Downloaded iOS6 and this did not help. At my wife's suggestion, put the old battery back in and it work as expected. Contacted iFixit and they immediately sent a new battery, which worked when it was put in the phone. Now I am very happy, and impressed with iFixit's fast response.
If the phone is flaky when a battery is replaced, try using the old battery before doing anything else.