Was keen on Giff Gaff when my contract ended start of the year but i travel a fair amount and I find Giff Gaff extremely poor/expensive when abroad. They didnt have a european plan/package like other networks.
So went on Three instead, £15, month long contracts 200mins unlimited data/texts.
The best thing about it is their "Feel at Home" offer
which is where if you are in one of the 16 countries you can use your home as if you were in the UK. Unlimited Data etc
Ireland, France, Italy and the US among others.
I have spent about a month and a half in the states so far since getting the contract and i could use my phone as usual, google maps and whatsapp.
The coverage isnt quite as good though, was in Aberdeenshire over the weekend and hardy ever got any data