I've seen it, and it seems to be a decent welder.
As far as the controls being on the stinger, well, look at my stingers after a couple years, and for my money I sure don't want or need controls at the stinger.
I also don't like the idea of having to run the truck engine to weld. In most repair welding situations, a lot of time passes between actual welds, and I doubt the truck engine needs the extra wear.
More importantly, I really don't want the hood end of the truck any closer to the welding than I have to have it. Them neat little flying globules from burning rods do a magnificent job on auto windows and windshields. I really don't want to spend the time to cover the windows and cab with a blanket either.
All things said, for a guy who only needs a welder an hour a week or so, and is always able to get his truck right up to the job, it's a nice machine. For a cross country dune racer, it's probably a great machine. For an off roader, again, probably a great machine.
Cost comparison, I think I'd buy a Miller or a Lincoln before I buy one of these. Either of them will outlive the truck in a maintainence application, and they won't be out of service if the truck gets crashed or is in the shop for some reason. I dang sure know if my truck gets crashed I won't be arguing with the adjuster about the repair or replacement of an aftermarket accessory.
I also know I can move the Miller or Lincoln from one truck to another in 5 minutes. How fast can I transferr a Zena?