10 - 30 minuten
My 4S battery started conking out after 15 minutes suddenly but knew I still had some time to go before I could upgrade to a 6-Plus. I also wanted to keep the 4S around so the kids could play Minecraft. I ordered the 4S replacement battery kit and it arrived much sooner than I expected.
After reading the other reviews of this job I guess you could say the repair was relatively uneventful. The back shell came off easily and I was able to unscrew the four screws without problem. One the pressure connector plate came off I noticed the little ground clip had come loose... after a little cajoling I was able to place it back in the correct spot, reattached the pressure connector over it and finished up the job.
Upon restarting the newly renamed iLazerus 4S, I noticed a problem that appears common to this repair, which was that the hone couldn't find the 4G service I get through AT&T. After opening it up again to make sure the ground clip was clean and indeed touching the metal plate on the back of the phone, I did some research and found out a battery swap will cause the phone to switch off the "Set Automatically" function of the phone's clock (found in Settings > General > Date & Time). Turning that back on got the 4G running again and--viola-- an almost-good-as-new 4S!
(One more thing-- the battery that arrived appears to have about 90% life in it; I guess that's more of a function of the age of iFixit's inventory for this particular model. I don't mind so much, since I was just looking for something to tide me over until I upgrade, but others more interested in getting the absolute most for their money might want to check their battery life via the iBackupBot application.)