I had a couple of Dahon 16", eventually sold them on eBay. Fine for a mile or so, not so good beyond that. A unicycle can be quite fast, especially a geared one, but that is a horse of a different color as the expression goes. If you want to go somewhere, get a Montague. It is a real full sized bicycle in every respect, with no disadvantages from the folding mechanism. We have two on the boat, in the garage.

I used to ride a unicycle to college. It had the advantage that in the sections of the campus marked "walk your bike" you could just ride right through, because a unicycle is not a bicycle (though not without the occasional argument from the campus police...). You could also take it on the elevator and in to class, with no askance looks or raised eyebrows. One more advantage is that it can be ridden at walking speed, so that going along on a crowded sidewalk or through busy plazas was easy.