Short form, here, is that ID is complicated, yes, but worth investing time into learning. And as for GIMP... it is and always was a free Photoshop clone; now that you have the real thing, which absolutely nothing else compares to, you might find a few hours learning a somewhat different interface and terminology well worth the time. Whereas I can only think that hours spent trying to integrate GIMP into the Adobe set is, just perhaps, time not as well invested.