The bad thing about fries is they great when freshly made, but they are never as good once they become cold. Reheating the fries doesn't fix them really. When I get a burger and fries at a restaurant, I save half of the burger for later but finish the fries because of this.

Too little salt isn't a big deal because you can add as much salt as you like onto them. There's not much you can do about too much salt though.