So far this season, the cargo box has been perfect. I bought it heading into our family beach vacation. I wanted something to keep the beach toys, sand, chairs, and wet items out of the car (things we wouldn't need to cart into the rental condo, but would use frequently). Suited this task perfectly. Better than the cargo bags because it tolerated the rain that comes with being at the beach. I also really like opening from both sides. I used it again to go camping. Two big pluses: #1, you can get your food and gear up and safe from animals, #2, get things out of the back window for driving. You've got to remember you have something on the roof, but the ability to load, lock, and go while keeping it all dry is great.
If you can't keep this on your car, it's a pain to have to store something this size, but that's not a product problem.