There are some Terms of Service [1] items that might come and back and bite you (or not — who knows, they're a bit vague):
The Service is offered in the United States. We may
restrict access from other locations. There may be
limits on the types of content you can store and
share using the Service, such as file types we
don't support, and on the number or type of devices
you can use to access the Service.
The fact that they "may restrict access from other locations" could be a problem when you travel.
[1] http://www.zdnet.com/article/is-amazons-online-storage-reall...