N.O. products have essentially been proven to be a bunch of bunk. The nitric oxide action makes you feel a temporary pump when you're working out, but doesn't do squat with regard to muscle or strength gains, fat loss, or anything relevant. In fact, some think that it might even be slightly unhealthy overall.
The kitchen sink N.O. products (like N.O. Explode) rely on a few things to make you think they're "working:" (a.) That pump feeling from the nitric oxide, which people falsely assume means that "My muscles are growing!" -- (They're not.) -- and (b.) other ingredients, mainly stimulants (like caffeine -- notice that in the ingredients list?

) and some other cognitive/energizing agents that make you feel energized. They also sometimes throw in some beta alanine, but beta alanine doesn't really do any good in a one-shot, pre-workout dose. You've got to take it several times a day, every 6 or 8 hours, EVERY day, consistently, to reap any benefit from beta alanine.
So in short, the N.O. products are the biggest buzz right now, but they're a waste of money. Purchase relevant ingredients/supplements on your own -- and use them CORRECTLY -- and you'll both save money and be much better off. Beta alanine, creatine, a good pre-workout product/energizer if you like, a proper post-workout formula (might want to mix that up on your own too), etc.