Hmmm... what tool did you use for the recolor? Paint brush? Pencil? For something like this, i recommend you use the magic wand to select the area and bucket fill it. Raise the threshold just enough so that the orange or yellow is selected, then fill it using the bucket tool. if you use the pencil or brush, you might not get to every spot. if you don't have a tablet or have gimp set to pressure sensitive, i recommend this. if you do have a tablet, try setting gimp so that different levels of pressure changes the brush size. i hope this helped!
In my opinion, it could use a bit of work... It's lacking in dimension. I'd recommend using the magic wand to select the hair, then from there fill it in. Adjust the darkness on the color little by little, based on what section. For example, the darkest part of the hair (sort of salmon colored) should end up kind of maroon. Hope this helps.
I'm not that familiar with gimp, but (since it's similar to PS) you should be able to add a new layer above the original image, paint (fill/trace) the section of the original you want in the new layer, then change the layer setting to "hue" instead of normal. That's how I do most of my color changes anyway. It looks alright, save for the few spots it appears you missed and the original shading/lighting not showing through too well. All in all, good job ^^
