Overall good. The d-pad could use work and isn't quite as good as the original. I'm also not a fan of the springy Z-triggers, since the original was not analog. It's my main complaint. It makes barrel rolling in Star Fox less comfortable and reliable. Has a death grip on the controller/rumble pak too.
However, the buttons are just fine and the control stick is the star of the show-- it's much more comfortable than the original, and more accurate than replacement sticks for the original. The layout of the controller is generally good for most games, and is excellent for some like Zelda.
Unless there is a specific need for the original, like an accurate d-pad or z button, this will probably be my go-to controller for the system just because of the stick alone.