Yep. It may not be as nickel slick as the ones you pay for, but it does all the tricks and the free part is an honest free.
We might have talked about this before, but content aware, and brush tilt control, make GIMP an anachronism. Sure it's better than paint, but the people who say "it can do anything Photoshop can do," know dick about what Photoshop can do.
I'm not a graphic artist. I'm an interpreter and would-be writer. My concern over what GIMP can or cannot do goes as far as my concern over the concept as a whole.
Well, this probably goes beyond what you're working with, but if you do have a heavy duty camera, GIMP can't process RAW files on it's own. That's kind of a big deal There a plugins that kind of do the same thing, but if you have a problem, documentation is sparse on the ground. Same with their resynthisizer plugin. It's no longer supported, and had a...variable...success rate. And Resynthesizer won't install on any Mac or Windows past 7. Similarly, the GIMP answer to content aware scale hasn't been updated in over two years, and has a whole forum comprised of people trying to get it to work. If you want a huge plugin community with a wide variant in reliability and documentation, GIMP can be good for you, I guess.
Also, in case someone is reading this for software advice, if you're looking to paint or draw your cover, instead of using photo manipulation; I can't recommend Corel Painter enough. It is absolutely worth the extra $500 you will have to sink into your hardware just to run. It is really, truly, just like painting, and blasts Photoshop out of the water. There isn't anything else like it on the market.