We had our dog done hen he was neutered 2 weeks ago. I didn't like the thought but like the thought of it could help he ever gets lost or something.
I don't think these things are going to hurt human or animal really, my pup doesn't seem to have an issue. Heck I have titanium mesh and screws in my head and I'm fine.
Not sure exactly what my thought are though on microchipping ourselves someday.