I have an inversion table outside, and I finally put up the bar in my doorway.
I still have my gravity boots that I bought back in the 80s.
I'd say blood rushing to your head is good for the hair, probably the heart, and it's definitely good for the spine.
It's can be hard on the eyes if you hang too long. What "too long" is probably different for everyone. Get a table and experiment.
Addendum: There truly is a difference between an angled inversion table and gravity boots which allows you to hang completely upside down. The free-hanging with boots is much more severe than upside-down angled hanging, but both basically do the same thing.
Addendum II: The photo is not me.