It is not risky if you already had experience opening up laptops etc, but if you don't, the biggest risk is breaking some of the cables. (There is really no risk when it comes to screws other than losing them -- make sure to organize your screws well.) And the solution to that is simple -- religiously follow all the instructions here, don't use force to pull something out when it does not come off -- make sure you are always doing the right thing. If anything seems confusing to you, find a Youtube video and follow what they are doing. You'll be ok.

Overall, it looks like a compact, high-quality power supply.

I don't believe anything about "high-quality" of the power supply, as someone who replaced the power supply twice and has seen numerous reddit threads about people having the exact same issue (xbox does not turn on) and replaced their power supply.

And can't agree on the repairability sctore. What a pain it is to get that power supply out. I am good enough at this so that the whole process takes about 1 hour. Many people spend 2 hours or more (as can be seen here).