Purchased for use on a roadster (Mazda MX-5) in order to protect against leaks and the hood from dust and rain during periods of inactivity. The size Large that I chose may have been a bit big for a small roadster like mine, as it covered 3/4 of the front hood and half of the trunk!
As protection, it is good as it does not let rain and dust through, while also having a soft interior lining that protects the paint.
Under the sun, it slightly reduces the temperature inside, but don't expect to get in and find it cool... it is just more tolerable than using only the classic windshield shades.
However, the plastic hooks are of poor quality and do not seem capable of withstanding the test of time. Also, in case of strong wind, I do not recommend having it on the car, as one of the hooks is likely to come off and start whipping the car, with all the consequences that this entails for the paint.
Overall, it is OK for short-term use, in sunny or mild rainy conditions, but not for long periods of inactivity or for use in severe weather conditions.

The straps are a joke, they didn't last even 2 days. The hood is indeed waterproof and well made.

Update after 6 months.

The hood has a huge negative aspect, if the inner fuzzy surface gets wet (if you cover the car with moisture or if it gets punctured at some point and water seeps through), it becomes like a towel-sponge and because the hood is waterproof on the outside, the water gets trapped underneath without ever drying. It causes problems with the color and rust. A semi-waterproof one that breathes is a thousand times better.