Having both versions in my possession, I have not noticed any other visual or technical changes. By cons, official controllers Wii or Wii U widely held longer charge (five hours more on average) that unofficial, and above all, the true Nintendo does not boguent!
For the price difference between the Wii and Wii U, on Amazon, the Wii U is often less expensive than the Wii; when my purchase, I paid 44 euros, and the Wii version was 49.90. But it also happens that the other way around, check well before purchase!
Well, after many hours of use, I am perfectly satisfied and I would buy the same color, blue or pink (the same price) if I needed another.
In conclusion, even if the Wii U in his beautiful blue box does nothing more technical (since most motion function was already integrated into the former), I did not think twice before buying this controller !