I have one, used mainly as a decorative item. They're ok for a nostalgic pot of coffee on occasion. About wore myself out grinding for more than that, though. Not against tradition --my pot of choice is a 60yo vac pot. But my regular coffee grinder has to plug in to an outlet and come with an on/off switch. I think if you hand grind for very long, you'll be looking for a powered version.
Zassenhaus is great, but IIRC they are no longer in business. You can find other good quality hand grinders on ebay. German made grinders tend to be well made. Hand grinders last a lifetime and good ones give excellent results even for espresso.
I use one at a shore house for two weeks every summer vacation. It does take about 5 min. for two pots of coffee. I don't mind it, but prefer an electric burr for everyday use. A friend prefers the Zass I gave him for everyday use. He actually likes grinding by hand!