I have been using the GIMP for a couple of years, but I found that it really had too many features for me. Based on a recommendation from John D Cook, I switched over to Paint.net. Paint.net serves my needs a lot better than the GIMP does. It is simpler, so I feel like I am making better use of the power of the program, and things are easier to find. I just find the toolset easier to use, although it honestly strikes me as more like the old MacPaint than Microsoft Paint.
John D Cook also recommended Inkscape as a good vector graphics program, but I haven't yet had the time to investigate it.