Full user review
"Like a free version of Photoshop"
*Take It with you, no install required
*Layer Operations (Overlay, screen, multiply, many many more)
*Brushes, Pens, Lines, Curves
*History Pane with History
*Batch Resize, Watermarks
*Unsuitable for someone who is not capable of learning a new feature rich application.
I really cannot say anything bad about this application. You can replace the layouts to actually mimic Photoshop, google "GIMP Photoshop Layout for GIMP Portable".
I also like the fact that you can go File -> Create -> Logos -> Starscape type a bit of text and job done! Well maybe depending on what the job is for, but the point is that for a novice user, it doesn't get any simpler than File -> Create -> Logos. the script engine allows you to take this concept to the extreme and build your entire web theme / application theme portfolio of images algorithmically in Script-Fu.
The built in tools and filters for GIMP are extremely flexible, offering much the same flexibility found in Photoshop. I have used GIMP for many projects, eg. Creating an iPhone App style icon. I have always recommended it to co-workers and friends. It may take a little time to get use to, but so does Photoshop .. and for free you cannot go wrong!