2 - 4 horas
I purchased my Mac Mini (mid 2011) and the iFixit 2nd hard drive kit on the same day. They even arrived on the same day! I wanted to use the SSD I already own as a boot disk, etc, so I needed tho apart.
The repair went smoothly. Just follow the directions carefully. If you've never dissected a computer before, this repair modification may not be for you. Being comfortable working inside a computer the repair went quickly and painlessly. Getting the power supply out and back in was the most challenging part.
A few days after installing the kit, my Mini wouldn't boot. I could get the new drive to mount via target disk mode, but only occasionally and not in its full capacities. I ended up opening the mini and found that the new cable was partially disconnected from the sata connector on the logic board. I attribute this to there being too much slack on the ribbon cable because it needed to be "forced" back toward its origin in able to get the connectors to line up. I noticed the dotted lines, presumably there for bending the cable for optimal routing through the Mini case. I made a few bends on the dotted lines and, voila!, the connectors line up much better now.
So that is something for owners of this kit to keep in mind.
I should mention that I was moving my Mini about, carrying it in my backpack several times, so maybe the motion of the mini and any G forces I exposed it to were to blame, but I don't think the cable should come disconnected. Seems the cable is just a mm or two on the long side.
Overall - very glad I have it and its working again! Thanks iFixit!