For those expecting an uninterrupted plug-n-play experience for PC, this is not the right gamepad for you. In this case, it's better to choose something like an Xbox or 8bitdo.
But you won't find a better gamepad than this in terms of value for money; I don't understand the negative reviews saying "waste of money, doesn't work," etc. We have become lazy and indifferent as a community, no one is willing to "get their hands dirty," and if it doesn't work on the first try, they immediately mock the product.
The reason it doesn't work wirelessly, as many friends mentioned in the comments, is because it works like an Xbox wired and like a Dualshock wirelessly, which is partly a big blunder by Powertech for defining it this way, but perhaps for reasons of multiple compatibility and technical limitations led to this design.
To explain so you understand why this happens, it's because all modern PC games are based on Xinput mapping (Xbox button mapping); think of it as a communication protocol between the PC game and the controller. The problem is that the RR-0021 communicates wirelessly only with Dinput mapping (direct input button mapping), which is a very old standard that games used to have before 2005 and earlier.
The difference between Xinput and Dinput is that Xinput is directly defined just like the buttons would be on an Xbox controller. Dinput did not have such a standard and is excluded from the same manufacturer at that time regarding the numbering of buttons. Those were dark times back then.
The controller was designed with appreciation and priority to be compatible with PlayStation 4 and then other compatibilities for PC, Android, PS3.
However, if you think that playing only wired for PC is a big mistake. The whole huge disadvantage is fixed with the magical and beloved DS4Windows application. The only thing you will obviously need is a simple Bluetooth adapter to make it work.
If you are not lazy and have time to learn how to use DS4Windows, you will realize how fantastic a device you have in your hands. By default, all buttons work in Xinput format, the touch sensor works like a mouse, and the touch press acts as a left click, and the 6-axis gyroscope works in games that require it. Of course, the programmable macro buttons ML&MR are not recognized in the application because this function is exclusive to the device itself, although I doubt it will ever be useful to you.
The thumb sensors are indeed magnetic hall effect, which means they are sturdy and reliable with much greater accuracy in relation to two axes. The easiest way to understand that they are indeed hall effect is in the button statistics within the DS4Windows application; you will see that if you rotate the sticks 360°, it presents a perfect circle within a square indication.
All the buttons, although not silent, have a very sturdy and tactile feel; it’s not like touching cotton, and they respond immediately to pressing. The "triggers" L2&R2 have very good resistance and work across the full range of pressing like 0-100. The touch area works as it should, and their sensitivity is correct, although I don't like the behavior of the pressing because it has a minimal slope.
Everything, and when I say EVERYTHING (except for ML&MR), buttons can be customized to your needs within the DS4Windows application, as well as the RGB LED indicator can adjust the color based on your preference.
Of course, as I mentioned, the device has a 6-axis gyroscope and works without further actions with the default profile in the application I have already mentioned so many times (we're talking about DS4Windows) and even these are adjustable in sensitivity, calibration, and function.
However, the amount of uselessness in the user manual from Powertech/Roar is unforgivable; you have very limited access to information, there isn't even an official PDF manual from the company, and the source of useful information you will receive is from skroutz or other social sources.
So, to summarize, aside from the pathetic user manual and the lack of Xinput in wireless form, all the major problems are solved with the DS4Windows application. The button has the same good build quality as devices above branded devices and is far more reliable. It requires willingness to engage and not to jump to conclusions quickly.
For €34, it is a crime not to buy it; there is no better option in my personal opinion. It is not a perfect device, but that won't stop me from giving it a 5/5 star rating.
Get it and don't say a word.