We use CaxtonFX cards all the time abroad, both in Europe and the US.
We find them completely hassle-free and the exchange rates are pretty good too.
We use them both to pay for things..hotels, restaurants shops ...and to get cash. The cash advances so far have always been free.
You do have to use up the money on them, though as it is quite expensive to have it refunded. Not a problem if you don't load too much on in the first place and keep an eye on your spending.
If you have internet banking and secure access when you are abroad you can reload any time.
I wouldn't be without them now. Cheaper than using a credit card abroad, safer than carrying lots of money and much less hassle than traveller's cheques.