It's probably one of the highest quality emulators out there. For example it is fully compatible with the Gamecube and Wii controllers using your computer's Bluetooth. They've reached a level where the console can even access the Wii Online community and appears to Nintendo's servers as a legitimate Wii (you still need to grab the encrytped blobs from your console though).

To all intents and purposes they've completely emulated a Gamecube and Wii and then gone many steps further in improving audio and graphics (original Wii is capped at 480p - Dolphin can go to 4K or beyond with visuals rivalling even the new Nintendo switch).