2 - 4 uren
I wanted to put a SSD into my 2011 Mac Mini, to speed up the boot time, and also just to learn something new (I love learning new things). The project looked straightforward and I had a 60gb SSD left over from another project. The iFixit kit was attractively priced, so I decided to go for it.
It went very smoothly. I followed the instructions and looked carefully at the photos (increased the size of the image to make sure I was seeing what had to be done). I didn't have any of the problems people mentioned in the comments (maybe because I took time to read all the comments first). I think it took me about 45 minutes (I took a dinner break in the middle).
Most of my repair and construction work has been on PCs, so I was accustomed to connectors that slide onto pins, rather than the Mac style of connector that snaps onto the pins. Mac style is definitely easier to deal with.
If you read the instructions carefully from beginning to end before you start, and if you read all the comments to see where other people have gotten stuck and how they solved their problems you'll do well. If I, a grandmother, can do it... anyone can. :)
OH! And buy a magnetic project mat along with the drive kit! You will be glad you did!