I have both and I much prefer GIMP. The layout is better (in my opinion) and it is much easier to use. I mean you need to watch hour long instructional videos to learn how to work Photoshop, whereas GIMP is basically self-explanatory.

i use gimp to make a template (draw the picture) and photo shop to render the images
P.s. check what i made through this technique here its the banner. http://forum.toribash.com/showthread.php?t=149894

nah photoshop has better brush strokes than gimp, definetly photoshop

I have both. I prefer gimp because it's a lot easier, with a simpler layout. But yes, as mentioned above, I dislike the brush strokes, as well.
The price of photoshop is easily overcome. though, it's not such a big problem as people see it. It's not too hard to hack, and you don't get any viruses. Although a few functions are disabled in the process if you do it the way I did.