How do mini penny-farthings ride compared to regular size pfs? I'm considering buying one of these with a 28" front wheel, pneumatic tires and rear caliper brakes. How do they compare to actual penny-farthings? I've read on another forum with unreliable responses (non-riders giving opinions based on movies) that any high wheel bike should only be ridden on pavement to keep from taking a header. Would this be an issue with the kind of bike I'm interested in?

I wasn't actually asking about functionality as a commuter bike. For that I like a cruiser. I want something to have fun with. Oddly enough I don't like heights so penny-farthings make me a little anxious. I suppose it's from being fairly high up without much of anything beneath me. I do know that it is necessary to pedal against the bike when slowing down. Applying the back brake first is helpful in preventing a header within theory. Most people walk a penny-farthing down hills. True penny-farthings have solid rubber tires. This one has pneumatic tires. The big wheels are supposed to just roll over ruts unless they are big ruts. This front wheel is much smaller. Does that mean that it takes a header over every rut? The high wheel bikes put the rider almost over the pedals. This one technically puts the rider slightly farther back since the legs are longer in relation to the radius of the wheel. Does that help keep the bike from flipping forward? Sorry to be so techincal but that's sort of why I was hoping someone here rides one.
My impression is they're a toy only, not to be used for travelling, just tootling around a park or around home.

My unicycling coworker has said that they are essentially unicycles with a training wheel, and are a lot of fun for playing about.  Also, I've seen video of them being used in street performances like a juggler or similar.

But no, you wouldn't commute on one, and the ergonomics would make training on one uncomfortable.   The 29" wheel would suit a kid, not a grown adult.

Additionally, with no gearing, their top speed is limited  to one wheel circumference per pedal revolution.  So this 29" wheel will have a rolling circumference of about 29" x pi or about 91" or 2.3 metres.  At 60 and 80 RPM that would be 8.2 km/h (5 mph) or 11 km/h (6.8 mph) which is a fast-walk/slow-jog to an "average runner's speed".

Said another way, they probably fixed gears so you cannot coast, you have to pedal.

The rear brake will be mostly useless - the common wisdom is that the front brake of a bike does most of the real work of braking.  Trying to stop with the rear brake only simply drags it out longer.  Your mini-farthing will likely stop poorly on brakes, relying more on fixie-skills like reverse pedal pressure, and that its overall speed is low.

I'm sure they're a lot of fun, but not a lot more than that.  With practice and good technique, I'm sure they can be ridden all sorts of places, but perhaps not aggressive/risky offroad/downhill etc.

  Example of a MPF with quite a lot of rake.

 Highly vertical forks with minimal rake.

The two bikes above would have massively different handling - no conventional bike would risk having such a vertical head tube.