I love using an Airbrush and although they are tough to master, a gentle persistence and experimentation will reward the user.
Anyone dabbling in art should try them out, they are a top addition to any artists toolkit.
An Airbrush will replace nothing you already use, but they will add greatly to your available resources. The time they can save you is tremendous.

I have six Airbrushes....
(2) Passche H, (1) Paasche VL, (1) Aztek 2000 and (2) Iwata HP-C.

Paasche H	Paasche VL
Aztek 2000	Iwata HP-C

I use them to color a great deal of my work.

Acrylics, Watercolor, Gouache, Inks and Dyes can be used with an Airbrush. They must be of a Airbrushable Grade though.

I like doing murals, a big picture is a good challenge and allows greater detail. I also get a lot of public interest in airbrushing 4WD spare tyre covers. They are good advertising because of their obvious mobility.

The same applies in airbrushing Bus rear windows, they are mobile mini murals.

I still have a lot to learn about these wonderful tools - (how much is too much anyway?) and every day is a learning day for me.