GIMP is a bit of a learning process from Photoshop, but once you know where everything is in translation, it's really not too bad. I moved entirely to Linux and while I have feature requests for GIMP, it hasn't held any of my art back.

Their window/toolbox system sucks though. I have a hard time placing all windows where they need to be and even opening some of them. It's probably my biggest complaint right now.