Finally, a plastic medium format camera with auto-exposure. In my view, poor exposure control has been the main limiting factor preventing wider popularity of these kinds of cameras with photo enthusiasts. They usually have two apertures and a fixed shutter speed (plus bulb). Having the ability to adjust exposure over a wide range of lighting conditions, manual or automatic, is the real improvement here.
I have the Holga GSN-120, a glass-lensed version, and the center of the images really is pretty good, enough so to warrant the extra cost. But again, limited exposure control is the downfall, especially considering the cost of processing and printing color 120 film at a lab. Spending a bit more money up front for an auto-exposure 120 Lomo will pay for itself over time in the images you would otherwise not ruin due to faulty exposure.
As for zone focus, what I've done with my various Holgas is affix numbers to the lens barrel with the distances in feet for the four settings. i've found it very easy to estimate subject distances within the DOF tolerance of the lens aperture. Easy-peesy.
~Joe