What are the advantages and disadvantages to taking nitric oxide?

I'm thinking of trying it but I want to know exactly what I'm expecting. Can it cause health issues? Does it speed up metabolism? Does it strengthen the immune system? (I heard that it does) I'm going to start working out this summer and I need quicker results. Oh yeah and can it help some one lose weight pretty fast. My friend is a little overweight and he's been looking for ways to get thinner. Please and thank you!