After testing these picks for a while on the electric guitar I'm definitely not a fan.
The sound produced by the pick is good, warmer than the "classic" tortex and the durability is clearly there.
Unfortunately the pick is so slippery that it feels really weird playing with it.
Playing with a traditional pick grip the thumb's fingertip makes good contact with the pick but it keeps sliding on the index part. I wonder if it would have been better with an embossed grip like on the good old Dunlop Nylon.
You could drill some holes in the pick to improve the grip but it seems like too much of a hassle for me.
To summarize : good warm sound (trust me), poor grip.