I've had a couple of these picks when i first started out 12 years ago, but i only recently decided to get some new ones.
Let me start out by saying that i play mostly metal, hard rock and everyhting in between. I'm looking for picks with a clear tone and fast attack.
If you're looking for those things as well, i'd advise you to find some other picks than these.
I found them to be a lot more mellow and dark sounding than Tortex or Ultex, and they arent as responsive as those two either.
The shape is a little weird as well, if you've been using regular flat picks like i have, but you get used to the shape after a little while.
Like i said, i play a lot of metal, so that means a lot of hefty downstrokes. That's something that'll really eat away at these picks, and relatively fast as well. A normal Tortex pick lasts me about a weeks worth before the edges are all messed up. These nylon picks barely lasts a day or two.
So if you're a metal player, and you're looking for new picks. Try something else!