I have one. It's really far from great. I can go into a lot of detail about how bad it is, but I'll be brief here.
* The shoulder buttons are segmented very very badly in a way that makes it awkward to use (see image)
* You have to press far too hard to actuate the shoulder buttons
* The D-pad feels nice enough at first, but it feels insensitive to diagonals.
* I can't describe why, but the D-pad feels clumsy. When I use it I don't feel like it's controlling right, even compared to the original NES, and especially when switching from left to right. It doesn't feel like it rocks properly.
* The analog sticks are absolute shit. They have a strong bias toward the axes (ie. you have to press twice as hard to get them to go diagonal as you do to get them to go straight up and down or left and right)
* The sticks require an inordinate amount of force to actuate the buttons given the awkward placements
* The sticks have no dead-zone, but hit full actuation at about 70% of its tilt (effectively meaning there is a 30% dead zone AROUND the stick, except for at the diagonals, where it is considered being fully tilt on both axes. Technically, this means that 70% is inaccurate, as the actuation amount would be 1 / sqrt(2), or about 70.7%). This does mean that the sticks are actually square, in terms of actuation, not truly round. This wouldn't be an issue if the whole outside of this area wasn't a dead-zone for its axis. It makes controlling 3D games awkward, as you can tell that movement is off when you're moving diagonally, but you can't quite put your finger on why it's so weird.
* They can only sync to one thing at a time, and in only one mode at a time, so you have to re-pair the bluetooth every time you might want to use another device
* The bluetooth range is absolute shit. It starts getting patchy at only about 5 feet away, and fucking forget it if the controller doesn't have a line-of-sight to your bluetooth device (luckily, it works in USB mode, so this is a minor gripe in most cases)
* mine came with painfully sharp corners on the d-pad, and I had to file it down with a nail file
* The face buttons feel sharpish on the edges, but it's not too bad
The good points are just:
* The start and select buttons feel nice
* The stick placement isn't bad, and they're compact and out of the way, not snagging on anything when stowing the controller in a bag or something.
* The controller stows and fits comfortably in a pocket
* The style of the controller is great
* The size and shape of the controller are perfect, and it fits perfectly in my hands
* The stick design of a rubber top on a plastic stick with plastic edges is actually a great idea, and prevents the rubber on the sticks from wearing off without sacrificing comfort.
All in all, it's a controller that wouldn't be terrible at $15, but even then kind of pushes it. At its actual price, just fuck it and get a Wii U Pro Controller. It's the fucking best PC pad around when you get it properly pairing to your computer.
The NES30 Pro and FC30 pro are mediocre controllers that look fantastic. I really do love their aesthetic, but a controller really needs more than passable face buttons, decent start and select buttons, and a mediocre to shit everything else.
Seriously though, get and configure a Wii U Pro Controller. I wish it had more real use on the Wii U, because it's a great controller.