It might be. The paint is not cheap so keep that in mind.
Actually, when you consider that the One Shot is in a 4 oz can, if you compare it to the cost of many model paints that come in 1/2 to 1 ounce bottles, it ain't bad. You would just need to buy it in colors you use a lot (4 oz paints a lot of N scale).
I don't remember it being particularly flexible, but on the other hand, it stuck to just about everything I ever painted it on.