The reason most "graphics people" say GIMP is horrible is because they are used to Photoshop and its way of doing things. The two programs are probably almost equally daunting to someone who is used to neither.
In my experience, the Photoshop artists (and to some extent, digital artists in general) hate anything and everything that isn't what they normally use.
That said, GIMP is a bit convoluted, as far as UI. But I would say it is a step up from the likes of Paint.NET at least.