Much cheaper than Nintendo's originals. You can feel the difference as the return to their original position is slightly stronger and pressing the stick in makes a pronounced click. Apart from the small difference in feel, I changed them 6 months ago and have logged about 150 hours of gameplay on them without any issues. I'm not saying they're indestructible, but instead of paying 50-60€ for Nintendo to repair them with originals that might last the same amount of time, it's better to pay 5€ for each joy-con every time one breaks.
However, nothing is certain with electronics as they can fail much earlier than they should. In the case of someone I know who bought the exact same ones, one of the two started drifting in the first week of use with normal play.
!!! Finally, note that once you open the controllers yourself for repair, Nintendo will no longer accept them for repair if you send them in.

Good quality has very small differences, it is very easy to change, you can imagine I did it by myself and I am 15

Quite good quality, the change was quite easy and the design is exactly the same so it fits very well in the place of the old one. Personally, I didn't notice any difference from the originals.

If you haven't opened the joycons before, and the problem is drifting, contact Nintendo first, as they are now obligated to repair joycons with drift.

Its function is very good, it has accuracy and fast response. The replacement is relatively easy. The console's screwdrivers are necessary for opening the controllers.