I have used an Adobe Photoshop lite version in the past and I don't have a recollection of it being bad, but recently I tried using Gimp to create some simple textures for a game and struggled with this simple task. I had trouble finding how to do really fundamental things like change the size of the paint brush or pencil, or where you can easily select a different color. After searching, I found out how to change the size, but then after encountering next challenge color, and even asking a friend, in case I was just being completely oblivious, he could not figure it out either. Maybe I closed one of the many pop up windows that I needed, and could not figure out how to get back. Overall my experience was very bad with Gimp. I gave up based on a recommendation by others to just use paint.net. Paint.net was very straight forward and intutitve. So at least from a non expert user viewpoint, Gimp is a very difficult to use UI.