The license is pretty extreme: you must have a revenue under $10K/year.
I love procedural textures (being artistically crippled myself), but I get by fine with pregenerated ones from FilterForge, plus it has a massive library of free procedural textures.
As cool as Painter sounds, being tuned for game textures, you can get a long way with Photoshop Elements (if you already have it) or The Gimp (free). That said, if you haven’t learned the hoop-jumping for any tool yet, Painter might be a great option. I’m too boring and accustomed to PS to even try the Painter demo