I dont, I think its horrible compared to nowadays controllers. But I guess if you compare it to the N64 controller its OK (who even has three arms?! Jk.). That said I have played my share of hours on both the gamecube and the N64 :)

It was so darn ergonomic. Nothing has ever felt so good in my hands. And I loved both the feel of the analog stick and how there was one central button with others around it. It definitely wasn't perfect, but if improved upon I think it could become the best controller ever.

because people love the gamecube controller.

The D-pad is too small, right c-stick is very imprecise and huge step back from having 4 c-buttons, the z-button feels unresponsive, the Start button is too small, the ABXY button layout is strange and the LR buttons are shaky. In my opinion the GameCube controller is the worst controller of any Nintendo system, even far behind the Wii-U gamepad or Wiimote. Best Controllers are SNES and N64.

I can not understand why the button layout is not the standard for all controllers. It is so intuitive and easy to understand. 

A slight update by adding necessary buttons and changing the D-pad would make it superior to any other controller in the market without question.
Other controllers have frankly not been as good outside of additional buttons and the the D-pad

I found it weird back then. My favourite controller was snes' and I still think it is. Nostalgia talking, of course :P

This. Awesome controller.

cuz afther that we got this:

and this:

No f*cking clue!    It is inferior to PS2, PS3, 360, X1, and even the original Xbox (Not oversized version) imo.