From what i've read at the couple of forums I post at, the majority of people take this as a marketing scam by the oil companies based on a few reasons:

1.) Nitrogen is an inert gas that doesn't burn. How can adding this to my fuel possibly help?

2.)It's just diluting the gasoline

Basically, everyone thinks its a sham because shell won't release exactly how it helps. All they do is make claims of what it does instead of posting the science behind it. The only reason I can think of how it works is that the nitrogen added to the detergent helps keep the cleaner & carb build up prevention chemical from burning off during combustion. I have no proof other than my own theory, but when I find it i'll post it.

Hopefully shell lets the cat out of the bag soon, otherwise this ploy of theirs is being perceived as foul. If they are truely changing how fuel works as they say, there's a good chance we'll see some higher performance out of smaller engines in the future.