I've played through Twilight Princess for GC at least 6 times; I know it pretty well. Its phenomenal, and as you can guess there is plenty of replay value.
This review is about how the Wii version compares to the GC version. I bought this one after being pleasantly surprised by the Resident Evil 4 Wii Version. I decided the Wii experience might add to a game I already put in my top 5. Ultimately, no it didn't. I just played it through on GC 6 months ago, so my enjoyment would have to come from the ways it improved on the GC version.
The entire world is a mirror image - right is left, left is right. Eldin is West, Lanayru is East. It surprised me how little this affected my experience, considering how familiar I was with the other way. Otherwise, I did not notice a significant improvement in graphics.
It boils down to controls. RE 4 taught me that the Wii remote made aiming easier, but it didn't here. To complicate things, when you are using an aim-able weapon like bow or hookshot, and your pointer is offscreen, a message appears: "Point the Wii Remote at the Screen". Because your remote does not need to be pointed while using your sword, you tend to not keep it pointed, so when switching to your bow the message appears almost every time. Your pointer is shown as an inexplicable blue fairy, that makes a faint rattling noise as you move it. Annoying. Using the Hawkeye, you aim with the nunchuk but have to point and click on zoom features with the remote. Awful.
I was excited to see how special sword moves would work with the motion sensor. The spin attacks utilized accelerometers in the nunchuk and basic swings are slashes with the remote. This made the spin attack (and later the Great Spin) easier. The Shield Bash used the back and forth accelerometers in the nunchuk, which made it more difficult, even if the motion was congruent with the action. But most special moves were A button prompts as they are on GC.
So great game, but I'll keep my GC version.