I haven't tried it, but I think I saw a discussion about it on modsquadhockey not too long ago. I think the general consensus was that you could feel a difference, but it wasn't game changing. And reapplying ranges from player to player.
Have you tried it? ... everyone thought the earth was flat till someone proved it was round ... If it's true that the NHL approved it this year and lots of junior teams used it last season then it would have had to go through a testing process right?
I was looking at it a few months ago based on the WHL Rebels success stories ... heck I drop 30 beans in the bar with the boys so what have I got to lose LOL