Don't expect 3G coverage worldwide. You'll be able to make phone calls (2G), but data transfers will be a) very slow, and b) very expensive. Usually, data transfers are not covered by plans, except special data plans. My suggestion would be open Wifi, since, in my experience, it's the better option in most cases.
"Life is not a journey to the grave with the intention of arriving safely in one pretty and well preserved piece, but to skid across the line broadside, thoroughly used up, worn out, leaking oil, shouting GERONIMO!"