The voices and textures are the way they are because we're limited to 40 megs for WiiWare titles. The PC versions of our games are usually 150+ megs, and most modern games range anywhere from 1-10 gigabytes or more. Talk to Nintendo about this one.
Frame rate issues will probably get sorted out eventually, but keep in mind that the Wii is just not a powerful console. An iPhone is much more powerful than a Wii, even.