I was excited to get this silicon sleeve in the mail. When it arrived, it didn't look like much, but it really makes a huge difference. I don't have a problem with hand perspiration, but whenver my hands sweat its while playing games. Strangely, now with this sleeve on, my hands never sweat! Not to mention its more comfortable to hold the controller and you have a better grip on it. I'm planning on getting it for my other controller too and recommending it to my friends.
A minor complaint is that the silicon doesn't bridge the gap and attach in between the bumpers and the triggers on the top of the controller. Instead, there is a gap there and on the right side of the trigger/bumper the silicon points upwards instead of wrapping around and onto the controller. Its quite difficult to explain but if someone saw a picture of my controller with the sleeve on it would make perfect sense. Its a very thin area, so I suppose they didn't want the sleeve to tear at that part. I just folded back a piece of clear tape so that it acted like double-sided tape and that part of the silicon no longer flops around. Nonetheless its a great product, highly recommended.