Annoyances: The humidity, Monsoon season, and for some the typhoons.
Health: The Local's are into health and exercise, ie eating mostly raw food, running outside at all hours of the night...
Interacting with the Locals: Be respectful, don't play loud music when you're driving, speak softly, dress modestly... the Japanese are respectful people if you respect them and their culture it means a whole lot. Also, try to learn the language that means so much to them.
Transportation: The taxi's are always available, they do not accept credit cards here on island, mainland Japan taxi's do, but not here. If you are in the Marine Corps the Green line buses are available free of charge.
Okay this kind of place is not for the new traveler! If you are not familiar with the term "Culture shock," come and visit Japan. At the airport, there are English translation but once your are out in the Japanese cities, you're on your own. Make sure you learn a few phrase like "Do you speak English?" That help me on the phone.
It is a wonderful, exotic, and life changing experience. Especially being American or European, be prepared to be gawked at as the tallest, fattest, well basically bigger than any Japanese people, particularly Okinawa. Oh yeah, on the island everyone wears hats, long sleeves, gloves, carries umbrellas, long pants, etc. to guard from the sun. It took me a while to get used to people walking around completely covered up.
I did love the fish market, but get there early to see and even buy fresh catch of tropical colors. The Japanese people, it seems, really do appreciate all opportunities that the ocean provides as meals.
Itoman is wonderful to see the suicide caves, tunnels, and cliffs from World War II. I was enthralled.
Hedo point is the most northern spot in Okinawa. It worth a drive becasue you pass Okuma beach where you can camp out right on the ocean front, includes resaurant, BBQ pits, and other emenities.
Okinawa is basically a Hawaii that speaks Japanese. It is a beautiful island and has a lot of japanese influence. Regardless, American tavelers should take note. Okinawa was the site of a seriously horrible battle between the Americans And Japanese in World War 2. The battle was a long one and there is a lot of documentation that you can find on it. Its a huge historical impact that I think is not well known and needs to be, it was as bad, or gets really close to, Iwo-Jima. Anyway, back to today, Like i said before, its Hawaii in a different culture. All you really need to know is common sense, being polite, try something new, and relax and enjoy yourself. And try not to underestimate the currency exchange rate, if its confusing, get a calculator and try and adapt to the use of whacky numbers. Other than that you should be fine.