The last time I took an N.O. of any kind was back in 2014. I was 25lbs heavier so there was really no visual difference and at that time I was also trying to fight that additional weight off. Now that it's gone and every ounce of effort I put forth is noticeable, N.O. Fury is a definite in my book. Absolutely zero jitters in my personal experience on it. It compliments my present stack nicely, as that surge kicks in, the N.O. F shines. I'm highly recommending this. For me, it's all forearms and calves that I notice this taking effect. As I'm still "embracing the shake" in other key areas, continued efforts will work that core and N.O. F will be part them.
April 2017 Update:
I'm still on N.O. Fury and still digging it.