I came really, really close to purchasing one of these about a year ago. Went as far as to call Unicell and talk to a rep about these boxes, because I have rarely seen them. They say they don't sell many of them, but they are made pretty bomb-proof (as most of the contractor boxes are, and unicell is one of the better manufacturers of those). They make a version with double doors in the back that would be preferable to that one large door... but I could also see where that one could have some cool aspects to it. Looks like this one has the ultra basic e-series cab (manual windows and such), which would also be a tad annoying.
The biggest selling point for me with these - they have 76"-ish of interior standing height. The majority of the box trucks are right around 68", meaning that a 6' tall person can't quite stand all the way up. I only wish that they made a 10' long version instead of the 12' one. Wilderness Vans out of canada converted one to 4x4 with a ujoint kit and i believe that they made it in to a sweet shop van. Their IG has some sporadic images of it.