I don't like it.
I just don't like wall mounted external power supplies hanging on by friction alone. (let alone putting a computer into the form factor).
There are not too many server applications I'd want hanging off a wall held only by a standard 120V plug. (note the lack of a ground lug - which would add some stability) If you plug it into a horizontal power bar no doubt it will cover the two adjacent plugs.
Why not put a power cord on it? Or perhaps bundle a mounting bracket kit so you can solidly anchor it?
The whole thing just seems too physically tenuous to me. Not robust.
Now if it used a 240V twist-lock outlet - totally different story. Such wiring is not that common however and its installation would defeat the whole convenience concept of the product.