She is also fun to read, being prepared to laugh at things that deserve it and to offer personal opinions, sometimes quite bluntly. I find BGP scary. It is configuration-intensive.
Routes can be permanently unstable.
It solves only whatever it happens to solve rather than providing a general-purpose solution. But we're stuck with it. Perlman roughly follows the protocol stack upwards. They share with you the warped way I look at the world, which is to notice and be distracted by suboptimal protocols in everyday life.