I have visited McDonald's in Norway, Sweden, England, Spain and the U.S. (NYC). I think the food and soft drinks tasted pretty much the same. The biggest difference was the restaurants. For instance, the ones in NYC had an outdated and cheap interior.
I visit McDonalds's every second month or so. I like the french fries with ketchup. In Norway the ketchup is served in a small cup (for dipping), not in a small bag.