If you have an iPod, "there's an app for that" It is a currency converter, and was very helpful on our trip. I say definitely use JA $ .... For example, we ate at 3 Dives, and dinner in American was $32.00, however, if we had paid in JA it would have converted to $28.00 American. I know it's only $5, but that adds up, and it is only one example.

But like Blake said... have both. We converted $160.00 to JA, and were fine for about 5 days. Plus, it's fun to say you have 1,000s of dollars!

Also, take some $5's & $1's for tips.