2 - 5 minutes
My friend had jammed his iphones power and home buttons, shattered the back of his phone and messed up the dock connector so that it wouldn't charge anymore.
The repair went great except for 2 things. I misplaced 2 screws so I need to take it apart again to find out which one I put where, the back cover won't close because of this. And also the power button replacement didn't work, I think it has to do with the bracket actually (not the button itself) but ifixit doesn't sell these parts so I got it from somewhere else. Otherwise the repair was easy to follow and fun!
make sure you know which screws go where. This is important