I've never been able to get Gimpshop to run either. GIMP by itself runs fine though.
I've tried to make GIMP my primary image editor, but I keep falling back to my old copy of Paint Shop Pro 7 just because it starts up so quickly and I know it so well. However GIMP has the one tool from Photoshop that I really love and that PSP7 lacks, which is the ability to paint on the mask layer.
GIMP has a little bit of that "all over the place" feel you get from OS apps sometimes. Like, effects are in two different menus based on whether they are binary filters or scripts. As a user, do I care how the effect works "behind the scenes"? No. But OS software is designed by techies for techies (what do you
mean you're not a programmer?
) and so the usability is not up to what you'd get from a commercial app like Photoshop. I still often find myself hunting through the GIMP menus for the function I want.
Also, the documentation is just sub-par. I want to punch my screen every time I see that "Eek! A help is missing!" message (which is
all the time!) To me, it's like I can hear the developers saying "it is so humorous to us that you can't figure this out, you clueless noob" in some vaguely Scandinavian accent.
But rants aside, I like GIMP overall, and it has really progressed recently. If you haven't looked at it in a year or so, definitely check it out - it's grown up quite nicely. It is a decent competitor for Photoshop for certain things, such as web graphics and hobby photo editing. It's not really capable of professional work though, due to lack of stuff like color calibration tools and its lack of support for CMYK color.