Fantastic tool for doing stuff. I've had more fun in this than I've had in Photoshop or any other digital painting program. I think it might be because it perfectly simulates a painterly feel, whether your thing is pencils, markers, paints, or any other thing you can think of. But the best friend here is the palette knife. I've used a palette knife in real life before, and swore off it because of its dificulty. Here however, I see it's advantages clearly, and absolutely cannot do without it!
The program is better with a drawing tablet, but found it work pretty well with mouse since you can mess with the sensitivity and flat out tell the program to ignore your scribbly mess and make it a straight or curved line easy.
So final verdict: This is one of the best digital painting software out there, and if you are even remotely interested in a cheap alternative to photoshop, you need to take advantage of it.