I wouldn't describe it as "not cold." It's true the temperature never gets horribly low, but it gets chilly and the wind and humidity makes it feel a lot colder than what it really is. I'd take winter in Hawaii over Okinawa any day.
Strange he said it was rarely sunny - when I lived there, it was sunny most of the time (outside of the winter). Granted, the weather would change on a dime and you'd get these ten-minute rain showers every day in the summer despite there being no clouds (which were a relief from the heat so we weren't complaining).