I believe that fits the definition of "difficult."
But you can't argue with
the results. I am not much of a bokehvite, but I'd love to give that camera a try. It definitely gets that large-format look in a handheld digital camera.
It's worth noting that a DoF calculator rates that lens (85mm f/1.2 on a 48x36mm sensor) as roughly equivalent to a 60mm f/0.85 on 35mm full-frame, or a 360mm f/5.6 on 8x10in large format. Wide, but perfectly reasonable. If you took a 200mm medium-format lens on 4x5in (long standard, like a 50mm field of view), an f/1.2 aperture would require a lens at least 167mm in diameter. Roughly the size of a salad plate, and probably well over 4kg. Impractical. But I bet someone's working on it.
The good news is that camera movements let you create the appearance of shallower depths of field, even if you're working with apertures that sound tight in 35mm and 1.6x crop photography. The downside is that you need a ton of light to make an exposure on the relatively slow films available for large format cameras.
Second vote for the 100ish-mm f/2.0 for portraits. My Canon 100mm f/2.0 is my favorite portrait lens. Both the Canon and Nikon versions are superb value.