GIMPshop is a modification of the free/open source graphics program GNU Image Manipulation Program (GIMP), intended to replicate the feel of Adobe Photoshop. Its primary purpose is to make users of Photoshop feel comfortable using GIMP.
I have been successfully using GIMP for what seems like years. It's free, it's stable and once you understand the rather strange menu layout, it actually provides fantastic functionality. But the reality remains that some people are still trying to come off their Photoshop dependency, and for these individuals, the argument about how fantastic it is tends to fall on deaf ears.