Retro controllers really bum me out, as many of them suffer from the same problems, and this one isn't much different outside of an odd design decision in that the only version of it that works with an actual SNES (the wireless version) has two analog sticks on it. How that makes sense, I don't know, but let's continue with the rest of the review. I'm reviewing the wired version, for the record.
As is the case with most of the "best" retro controllers, everything but the d-pad is totally fine. This controller, like many other retro controllers, is quite versatile, but it comes with the dumb usability issues that so many of these controllers have.
Instead of switching between DirectInput (default) and XInput with a simple switch, you get to remember which one of six unintuitive button combinations to use to switch between the two modes. Annoyingly, the controller defaults to DirectInput when you initially plug it in, though it does seem to retain its setting as long as the port it's plugged into is powered. Next time you plug it in, however, it'll default to DirectInput again.
Similarly, the controller defaults to the face button layout that appears on the button labels, which I'm sure works fine if you're playing SNES games on Switch but doesn't work so well if you're playing games that use XInput, thanks to Nintendo's terrible decision to dig up the SNES controller's bad face button layout for its "modern" controller layouts. Hey, what can you do? You can, of course, swap these with yet another unintuitive button combination, with the same rules applying as far as whether the controller actually retains this information between uses.
Now, the d-pad has three issues, though I could arguably condense two of them into one, but it's probably best to keep them separated with certain genres in mind. So, onto the d-pad issues...
1. Press the very center of the d-pad. There's no pivot point. The entire d-pad presses down. At first, I thought Retro-Bit made the horrible mistake of making the center of the d-pad function as a left analog stick press or something, but that thankfully doesn't seem to be the case. This lack of a pivot point really hurts the feel of the d-pad, though, as it's hard to know which direction you're pressing. That brings me onto the second issue...
2. The diagonals are too unreliable. Again, you've got what CAN feel like a pivot point, but using too much force as you glide your thumb from direction to direction will flatten the d-pad (since the entire thing pushes down), and it's very difficult to feel the exact placement of your thumb on the d-pad and know which direction you're pressing when the d-pad is flattened. You can feel the placement better with an actual pivot point present. Without a pivot point, since there isn't much distance between where your thumb sits on the d-pad between Left/Right and that same direction when it's pressed at the same time as Down, it's very difficult to control know whether you'll end up doing a Dragon Punch or Fireball in Street Fighter games, for example. Unfortunately, this same problem affects other things...
3. Good luck playing Tetris this thing, as you're very likely to hit Up on the d-pad when moving from Left to Right or vice versa. Oddly, though, that's not the only problem, as I tried to break in the d-pad with some firmer presses and found that the d-pad became temporarily less responsive in respects other than those I described in #2. For me, this resulted in being able to do full 360-degree motions on the d-pad again and again without my character jumping even once, despite me not using any attack buttons. Up on the d-pad simply wasn't registering at this point, though it did start working again when the d-pad "settled" or whatever it had to do.
This is a hard controller to recommend. I'd maybe play Mega Man X with it, but that's because there's no real consequence during game play to accidentally hitting Up or Down while running, since X can't crouch and doesn't require you to hold Up to trigger any special abilities. It might get a little weird navigating ladders, I suppose, but I otherwise wouldn't anticipate any issues. You could probably also play SimCity or something like that, as well, but that's because you don't need to respond quickly to much of anything. I wouldn't want to play anything else with this controller, though. This is a bad controller.