I usually like to stick to first party solutions whenever possible, but in this case, the way things are heading currently a third party solution is more than acceptable. The adapter came out of a situation in which Nintendo of America created an accessory to allow players to use Gamecube controllers to play Super Smash Bros. on the Wii U. Nintendo sorely underestimated the demand for this little accessory, which resulted in the accessory being sold out in stores everywhere. The only suitable location to pick up the accessory was on eBay or Amazon for insanely high prices, no doubt from people who wished to capitalize on the extremely high demand and limited supply. Thus, Mayflash devised a solution in the form of an inexpensive adapter, priced at $20. 

The packaging of the adapter is very simple, and very flimsy, unfortunately. The adapters, being mailed from Hong Kong, appeared to take a moderate beating in the transit. The boxes came crushed, and partially opened, no doubt by customs officials. The packaging contained no instructions, only the adapter wrapped in a mesh wrap to cushion the accessory. The visuals on the package indicated that four controllers could be connected to the adapter, which is attached to a Y cable which goes into USB ports on the Wii U. Two adapters could be used for eight controllers to be connected at once. 

As far as the adapter itself, it is a very solidly built accessory. The plastic feels sturdy, and very much like some of the old multitaps I used to own for the Playstation console all the way back some years ago. The switch, to go between Wii U mode and PC mode, is very solid, and slides easily with little to no force required to flip the switch. The cables themselves were very thick, and felt very solid. With Chinese accessories, the cables themselves seem to get gimped and become brittle and subject to tearing. This will definitely not be the case here. The ports for the controllers were very snug. I'm a gimmick freak, but the second port wasn't perfectly lined up, but it's hardly noticeable. 

The testing of the adapter was very quick. The adapter connected very easily to the Wii U, and does exactly what it was advertised to do - play Wii U games such as Super Smash Bros. for Wii U using Gamecube controllers, with ease. It's a very easy plug in and play solution. If you're having issues, make sure you check that the switch is set to Wii U play. The adapter also supports the Dolphin Wii/Gamecube emulation. By flipping the switch to PC mode, and connecting the cable to the USB slots on the computer, you get the same function. For vibrational feedback, a driver must be downloaded, by going to http://www.mayflash.com/Support/Download. The drivers are compatible with Windows XP, Vista, 7, 8/8.1, and Mac OS X in the 32 bit or 64 bit architecture. The controllers, once set up, play extremely smoothly with no delays noticed when playing Super Smash Brothers Brawl and Melee. I noted graphical lag, but this is due to playing it on an aging PC that is extremely behind graphically (Intel HD Graphics 2500!). The adapter performed phenomenally.

Overall, Mayflash did a great job. The solution provided is relatively inexpensive - $20 - and can be purchased on Mayflash's website at http://www.mayflash.com. Please note that due to demand, the first unallocated stock will be available on February 2, 2015, with earlier batches reserved for preorders. The solution is almost an exact copy of the official first party adapter provided by Nintendo, but for one fifth of the price. I would highly recommend this adapter to players who wish to utilize Gamecube compatibility - it certainly beats the wait on Nintendo! Thank you to Mayflash for providing GBAtemp with a review unit! If you are interested in picking up one of these FREE, you should check out my contest at the following link: http://gbatemp.net/threads/gbatemp-contest-win-a-mayflash-gamecube-adapter-for-wii-u.378515/ 

Good luck!