I'm not a heavy GIMP user but it imports/exports PSD pretty well, right? I was a heavy Photoshop user from 1.x to 3.x and all the basic features are there ;-) Color curves, hue-saturation, feathered selections, 99% of what you need to get shit done is the same as Photoshop. Granted, digital art is not my day job. So I don't know what newfangled tools Photoshop has now. I hate layers in GIMP as much as I hated them in Photoshop, I'm oldschool ;-)