I have to say it does clean very well, it actually removes grease from the strings and lubricates them to protect them from rust, that's its job and it does it, but...
sadly the plastic is very poor quality and it falls apart very easily if you're not careful, the grey part comes off and it stores a rug inside, which you use to remove the excess after lubricating the strings, but once you put all the parts back together the top black part always get stuck and you have to use some pliers to remove the top, it can get very frustrating and very unpractical pretty quickly, I just ended up keeping the rug laying around inside the case.
Probably the worst part Is that the felt soaked with the lubricant releases lint all over your strings, sometimes it get stuck in the saddles and that's pretty annoying and ugly looking, it's not like you can't play the guitar but honestly for an item branded fender I expected way more quality. I have to say that I like the effect of the lubricant on the strings, it makes them pretty slick, still I wouldn't buy it a second time, I would've liked a more practical metal casing and better quality felt.