I have it and used it to basecoat 2 40k armies scorched brown. It works, providing you dilute to the correct level, and it's certainly quicker than brush. However it burns through compressed air cans like no tomorrow, and you really, really have to keep it clean or it'll get blocked, especially with foundation paints which have the higher pigment levels.
So, it's basically worth the price you pay for it. For a single army, I'd say it's worth it in time saved.