Just a cheap piece of pine for me, previous owner has dented the inside of the tailgate from some heavy loads so I wanted to spread the weight across the door when I sit on it. Fridge slides out in the middle so the Mrs and I can sit down, kick back and reach for another beer.
If the pine gets too gross I'll just replace it with another, but so far its doing fine.
Used wood dowels to center the board with the factory holes; the board is only actually secured via 4 screws. The forces on the board are sidelong or straight down, the board only needs to hold its own weight when the tailgate is closed.
I've crawled in the back a bunch of times so far and suffered no knee cap injury. I would try to avoid the latches though.
As for value, yes, cant be beat. especially if you get it at black Friday prices. TBH, its about the max I'd be willing to pay for tailgate storage. If this option wasn't available at this price point I would have just tried to DIY something.