4/10 and 2 hrs for me on my 11 hatch...
The hardest part is getting those stupid plastic body panel clips off and finding the right tools. The actual install of the flaps is quite easy.
You'll need two stubby flathead screwdrivers (ideally less than 2" long) to pop off the clips, a small wrench for the front lock nuts, and a stubby (<2") Phillips screwdriver to tighten down the screws. It also helps to have a bubble level to align the flaps horizontally.
Tip when not removing wheels- turn wheels toward the side that you are working on for the front, and when putting on the rears, bend the steel bracket slightly to the rear of the car to accommodate the screwdriver length when tightening the inboard screw.