I like that item. I had rear window louvers (made by Visus) on the back of my last Mustang (03 Mach 1) that got a lot of compliments and they were very nice quality, but they were a PITA. Had to remove them for track duty as the high speeds would play havoc with the epoxy adhesive pads.
i was kind of thinking louvers, but at the same time i'm thinking of tinting the back window to like 5 %.
i haven't seen it on any cars and it may add that extra uumph where it makes people look twice and wonder what looked different but they couldn't tell at first glance.
I personally don't like it unless you add the sun visor across the top of your windshield/roof, rubber mud flaps that drag the ground, and parking lights across your roof, and maybe a step bar to get in the car.
I have it. I like it. Was EXPENSIVE for what you get. However, I got it because I liked the way it made the rear window similar to the 60s fastbacks. As with my retro theme, it worked well. Not many people notice, but the ones that do have never seen it before.