Very useful for travelers, good coverage worldwide and greatest feature is that your data never expires (as long as you purchase a top-up once per year)

Definitely would not recommend as it cost us time and headache while on vacation - just bite the bullet and pay for international plan with your cell provider

Worked fairly well in Europe - 3G. Terrible in China - edge

and it's just not used as much there (i.e.: most people have 3G capable phones only)

Also in the USA 2g has been discontinued by many phone companies and the last one t mobile is planning to drop 2g as well