My mom gave us one of these covers (not this brand, but similar.) It was almost impossible to install with one hand, which would basically have meant going to get the shopping cart and bringing it to the side of the car so that I could install the cover before getting baby out of the car seat. Used it exactly once.
If you're wondering about it as a gift for someone else--I notice babies in stores, since I had one myself, and I think I've seen maybe 4 of these in the wild in the last four years. So it's probably not even a great shower gift, or there would be a lot more people using them.