I got my order in the mail today and took some comparison photos with the original Japanese release figure. They do have some pretty noticable differences!
Aside from the different expressions, the american figure is slightly lighter in color. It is also slightly larger than the japanese one. The japanese one is definately sturdier than the american one (who has rather flimsy legs) but I think the american one is more true to the in game model, atleast IMO. I do recommend both figures though!
The new american one is pretty posable as well. :3
He has little paw pads too: