If you're just talking the liquid, it's pretty easy to use. I've refinished three guns with it, with very good results. I use an air-brush to apply.
The biggest thing is the prep work. Can go right over a parked finish, but a blued gun needs to be sand/bead blasted. Degreased and spotless before spraying it.
You essentially pre-heat the parts in an oven before spraying (essentially allows the acetone/solvent in the paint evaporate on contact, so it's 'dry' almost instantly), and then bake them in an oven after for about an hour.
It's best to apply in light coats. The metal cools down pretty quick after pre-heating due to the evaporation of the solvent. I usually need to re-heat the part twice during the coating process.
Before GunKoting, I had ZERO experience with an airbrush. Take your time, and make sure the prep work is done properly, and it will turn out fine.
DuraCoat (sold by a member on this board... Murdoc I believe?) is also a good product that does not need baking.