Personally, I've found that the term "International Driver's License" is kind of misleading. If you read the fine print, the document is not a license - it's a standardized translation of your home country license. And unless they've changed things recently it is not valid unless you also present your home country license with it.

If you're moving overseas, it depends where you're going. In Germany, for instance, the only translation they would accept of my US license was an "official" translation by the German auto club - so the International license was a waste. In France, it might be handy to have the translation if you're stopped by the gendarmes - but for getting your French license, there are only 8 or 9 states that do reciprocity with France, and for all the others you have to go through driving school and both tests (written and driving).
Cheers,
Bev