I like that it is very easy to use, has many tools for different types of diagrams (and you can mix them), there are free versions available and even more expensive ones with additional features.
It's not cheap though - maybe try some demos first? There isn't much else to dislike about this tool; everything works well and it's intuitively designed so that anyone who knows how to draw flowcharts should be able to get started quickly.
We're using it to design our internal processes in an effortβ¦