I bought these because apparently Nintendo can't make a controller that lasts longer than 5 months, so I went searching for a replacement with out paying full price. I chose these in particular because I like the look of the original joy cons and these looked similar enough at an attractive price point.
My first observation when I got them is how light they are, they are considerably lighter than the original joy cons, they also have an almost velvety or rubber feel whereas the originals are glossy. After looking at them next to the original gray joy cons they are several shades lighter.
They fit on the switch just like the originals but are kind of wobbly when locked in.
Eventually I loaded up smash to try them out and instantly noticed the absurd amount of rumble on these things, it was just to much and I had to turn it off in settings. The Main buttons (y, x, a, b) are slightly mushier than the originals. L and R bumpers are delightfully clicky. The triggers are quite bad, they bottom out so fast It doesn't even feel like I'm pressing anything, and makes it hard to press in fast succession. All the menu buttons are great and clicky. However my biggest gripe is with the joysticks. Their not silky and smooth like the originals and they don't have a grippy enough material so sometimes your fingers just slip off.
Maybe I'm being to nit picky but my final thoughts are this, you get exactly what you pay for. They aren't as quality as the originals but for the price point these are reasonably close enough to the originals.