Yes, I have a few, and I do use them from time to time. I keep one in my daily backpack along with an abacus; mostly just to surprise people when I don't pull out my phone to some more complex calculations that I can't easily do in my head.

Nice paraphrase of Sagan. :-)

This does look like a nice vocabulary builder.

But the only complaint I have is when registering it rejected my last name which has an "ö" in it, saying I can only use letters and numbers. (Which is also the case with HN. :-))