Yes, actually, I do like that crop better! It is definitely more centered, but the subject is still closer to the right. Anyways, the rule-of-thirds does not always apply!
Did you do some more editing to this second one? It looks to me like the shadows are a bit brighter, which I also like, the former one was a bit too dark.
As for GIMP, I can surely sympathize! I remember when I started using it, I couldn’t figure out how to do the simplest things, the interface was quite confusing, and I was lost! But I stuck with it; I wasn’t about to spend a whole lot of money on Photoshop, as I had already spent more than I liked on Lightroom! 🙂 I use it all the time now, and I don’t know how I would function without it. A large portion of my 2015 calendar was designed at least partially in GIMP. I’m starting to get called upon to help others with their designing jobs, so it is becoming even more indispensable!
Here’s a link to a little tutorial that I wrote up describing how I edited your image. Perhaps I’ll come up with some others later on, if you let me know something specific that you would like to learn.