1 - 2 horas
I have a 3 year old PS3 that crashed hard during a gaming session with the dreaded Yellow Light of DEATH. I wanted to get it working long enough to back up my saved games and data.
The repair went swimmingly. No roadblocks, and the whole process took about 2-3 hours. It wasn't especially difficult, though the reflowing process was worrisome (I almost bumped it while it was cooling and thought I had borked the whole thing).
Just follow the instructions, and be sure to keep some small dishes or trays around to keep all of those screws in.