If you’re at all wondering what it tasted like, just imagine a sausage patty with a bit of lettuce and teriyaki sauce on a McDonald’s hamburger bun.
The double cheeseburger was, well, pretty much like any McDonald’s double cheeseburger at any American McDonalds’s.
And, yeah, fries and drinks are smaller in Japan than in the US. Coincidentally, people in Japan are smaller than in the US. This is where statistics geeks say “Correlation does not imply causation!” with the kind of smug look on their faces that makes you want to smack them.