1 - 2 horas
I have a first generation model, and have no plans to upgrade due to the amount of PS2 games I own and play regularly. So when I experienced the YLOD and I was out of warranty so Sony would not fix the problem (as a matter of fact, said they COULDN'T fix the problem), iFixit was an easy solution.
Nice and smooth. Follow the written instructions on the webpage, they are much more detailed than the video.
It would be nice to have a "put things back together" portion of the guide. I know you say to just "go in reverse order" but that did prove trickier than anticipated. There are a lot of parts in this machine.
Make sure to keep your screws grouped by part. I ended up with a couple left over and had to go back and find where they went.