The shimmering is not the shimmering you are probably referring to, but a graphical effect to simulate the effect of the sunset. The aliasing is bad but most console games have it, and Wii is even worse because of the lower resolution of course.
I'm disappointed in the visuals here. It seems like it is degrading. :\ The image quality reminds me of an older PS2 game, unfortunately. The designs still intrigue me, though. Hopefully Nintendo sees fit to release this in North America.