While there are no issues using it, i personally don't think it falls under the smart for everyone catergory.
And yes i have used it.
Kit's can be expensive, extras for the kits cost good money too, then you have bottle refills, which in some areas can cost up to $50 a pop.
Nitrous money adds up, and while it does give you a kick in the pants now and then, a H/C/I setup is far superior for fun.
So if you want to go faster and you already have a h/c/i setup and cant' afford a supercharger, i understand it's use.
But if your engine is stock, spend the money on heads and bolt on parts instead, i guarantee on a daily basis the heads are more fun to drive.