In my Northern climate I don’t think my wife would ever use the pool if I didn’t keep a solar cover on it. The temperature difference is pretty significant.
If you have a heater, less important for “comfort” but it will save you a lot of money on heating costs by helping to retain the heat you’re adding.
That said, they are a pain in the rear. Having a reel in my case makes it less so. The more user-friendly/automatic you can make it the better, so it actually gets used.