Hi Morayeel, we have been back 1 week today with 2 children, 13 and 10, who have only lived in the US. They are enjoying themselves so far but struggling with not having their familiar foods. They are fussy eaters to some degree, but I think they'll come around.
My oldest is in touch with his US friends on Skype and Facebook and my daughter is also Skyping her friends, so they're not feeling like they're missing their friends yet.
We've just found a home and will be getting settled and started with school, so I'll have a better feel in a few weeks time.