Depending on where you live, you need to be careful about how/when the cover is used. A cover is great for low rain climates (desert SW). Sun and debris (dust, organic stuff from trees, etc.) is your biggest enemy and the cover is great for that.

But if you live somewhere that you have to deal with rain regularly, I don't think a cover is a great idea unless you can remove it BEFORE it rains. When the cover gets wet -- there's not a lot you can do with it but let it dry on the car. And having the sun bake moisture UNDER the cover day in and out isn't great for the paint.

I used one regularly when I was much younger more than a few decades ago. Learned my lessons then. Both my wife and I got tired of chasing out to remove the cover when the threat of rain reared its head.