I've been using Dunlop Stubby picks for years and they never fail to deliver. If you're into speed picking or shredding, then these picks should be on your list of must haves. Not only do they help in improved accuracy due to their rigidity, but they also help with a better attack.
My only criticism is when it comes to playing softer passages or acoustic guitar, where a slimmer pick is better, these can be a little harsh; but that isn't the products fault at all.
I've tried the 2mm version and they are also great but they are not as durable as the 3mm one when it comes to scraping the strings, etc. They groove very easily and that means that they catch slightly on the higher strings.
All in all, a great product and worth trying out if you've never used them before.