I would have to agree whole heartedly. Gimp does not have the versatility and effects that Photoshop has, but it is free and a darn good program.
Compatible with Windows, Mac, and Linux, multitude of tools RAW compatibility and a lot of plug ins make it a convincing competitor to Photoshop.
The only cons that I see are that it could be quite difficult to use for beginners and it has kind of a smushed interface. It also requires A LOT of plugins to come close to rivaling Photoshop.
I would say that Gimp is best utilized for dedicated users and those with graphic design as Photoshop is just easier to use. Then again Gimp is FREE.