From playing Zelda, it's quite easy to switch between close combat and combat with ranged weapons and using the Wiimote to aim is fun and easy (unless there's tonnes of sunlight coming in through the window; that screws it all up). The main gripe I had with MGS games was that it was really hard to aim with the analog stick and I'd often have to just spam a machine gun or something to kill somebody, and when I used tranquilisers, I'd often miss and I might gain the attention of the guard who would then run up and kill me or something.
With Snake already on the Wii in SSBB, do you think a true Metal Gear Solid game would ever make its way to the Wii? Maybe MGS Portable Ops could be ported to the Wii due to so many MGS fans not having a PSP.