I love the KontrolFreek grips! During this summer I found there was an issue with sweaty hands while playing due to the hot weather, and while the PS4 has dimples on the underside to help with slippage, these grips are a terrific addition. They are soft, comfortable and completely negate the issue of sweaty hands.
The grips come with great instructions and are fairly easy to fit. They have become an essential part of my controller!