They give off a nice clicky sound when you shake them. They seem durable and don't look half bad either.
The impact on the sound was immediate after I put a new set of strings, the guitar sounded phenomenal!
Now on to the Cons of this product, which are not few in number.
Beware that these pins are relatively straight and thick, measuring about 4 milimeters at the ends (0.15") so they won't fit into tight slots.(I tried to put them on a parlor guitar, and didn't fit the holes)
The groove of the pins didn't allow the ball end of the strings to slide in! One of the pins almost popped out while I was tuning the guitar. They act as if they are unslotted pins.
In the end I had to widen the canal towards the tip of the pinhead to leave a bit more space for the string to cross over the saddle.
This was my personal experience, maybe other were luckier, but other than some annoying design flaws, the pins greatly improve the sound. So that is that.