We engineers use this a lot for adding complex circuit diagrams in documents. The reason Visio is useful is because it can be embedded directly into office documents. But the problem is that I find Visio extremely outdated in usability (which is why I'm making the effort to voice my frustration here). .

Firstly, making a line is so difficult - the line is either straight or a circular arc. There's no (easy) way to make arcs of other types.

It is very difficult to draw up things - adding points to existing lines and manipulating them is difficult

Locking an item so that it isn't edited mistakenly is also tedious.

Layers should be present as well.

There is nothing much in the ribbon either to work with. the focus seems to be more on charts.