Okay, but which one?
Both the 2003 and the 2017 series are good. The older one has a raw style comparable to Serial Experiments Lain (with which it shared the director). The newer one is more sparkling and bright. They mostly cover different parts of the source material. If you can't choose, watch both.
What is it about?
Travelling around the world on a talking motorbike through small countries, with each country having its own specific quirk. Sometimes fighting people.
What's so great about it?
The world building and the stories that leads to.
Is it safe for work?
Yes, but the themes are pretty dark, so it's not completely suitable for children.