I really like the convenience of this magnetic filter system. You only need to thread on the base ring and magnets do the rest. Makes it less likely to damage the threads of your lens if you don't have to keep putting on and removing a filter on every time you need to use it. I am using this with a 24-105mm full-frame lens and the base ring works with the lens cap and the hood although you probably need to remove the hood to snap on the filter because otherwise your fingers get in the way.
Each of the filters themselves are quite a bit heavier than the screw on K&F versions, probably because they need to make the filter ring out of a magnetic steel instead of aluminum. Whatever the reason, they feel a lot more premium than the regular K&F version.
In terms of performance, its a bit of a mixed bag. I don't have tremendous experience using CPL and ND filters (this is my first set) so I don't know what's considered good performance at a given price range. Lets start with the ND: It seems to be close to if not a full 10-stops which is great; the previous K&F screw-on 10-stop ND which I returned clocked in at only around 8-stops in practice. The ND does have a noticeable color cast (see: photos of the sea right out of camera). Bringing the raw files into Lightroom, the ND image had 26 more points of magenta tint and was 1000K warmer than the no-filter image. This cast was reasonably easy to correct although the colors weren't exactly the same. Less correctible was the vignette at 24mm which needs to be cropped out. At least on my lens, a quick crop test indicated at I was loosing about 1 mm of focal length to the vignette. Note that since the filter is magnetic, there is a small amount of float between the filter and the lens so the vignette may not always be symmetric or consistent from one use to the next.
Moving on, the CPL filter (photos looking out the window) has similar vignette to the ND filter at 24mm but appears to cut down quite a bit of reflections in my windows. Not much for me to point our here, it seems to do the job.
The set does come with a UV filter but I do not intend to use it unless I am in a rainy/dusty environment where my lens needs a bit more protection so I haven't tested it out yet.
For both the ND and the CPL filter, I did not detect any noticeable decrease in sharpness caused by using the filters. However due to the color cast with the ND filter, I suggest either shooting in RAW or setting your white balance before putting the filter on.
For the price ($110) I think the performance of these filters is acceptable. I am a little disappointed with the vignette but I have heard of much more expensive filters having similar issues so I don't want to be too hard on this set. All in all, for someone like me who does this for fun, I think its a great system to learn the basics until I can justify the move to something more premium. If you're a professional and make money off your photos, then maybe look at something more upmarket like Freewell or invest the time creating a preset to fix the color cast.

All 3 filters for me are very useful. The stand-alone ring however, I'm wasn't sure how much I'll actually use it but surprisingly I just leave it on my lens unless it's pretty bad weather, which in turn I use the UV filter as a protective layer for the glass. Personally, I haven't found the UV filter to do much other than to protect my lens and because the glass of my lens is such high quality I don't leave it on as it could degrade the photos, that's why I use the stand-alone ring. I haven't noticed any degrading when using the UV filter so no complaints. As mentioned earlier, however, I only use it to protect my lens. The CPL filter works wonders and the ND filter is great for long exposer shots. the combination with the magnetic touch make this absolutely flawless. would recommend.