AGREED!!! Our problem, though I am also zone 6, is that any kind of plastic greenhouse on my property needs a SERIOUS wind blocker. If you live in a suburban area and you have 6 ft tall fencing AND can place it where the wind doesn't hit it AND you can get 6 hrs of sunlight every day, that could work.
If you haven't bought it yet consider starting seeds indoors, even on top of your fridge, then build a few cold frames this summer to extend your season next Fall.
I think if I used this greenhouse it would rip to shreds. It really looks flimsy. I think old clear shower curtains are stronger than this. Btw, THEY would make a nice cover instead of glass for a cold frame.