Render and BG seem low quality. Try sharpening the render. On the main GIMP dialog box, select the blur / sharpen tool -- it's on the last row, looks like a rain drop. Double click it and select sharpen and play with the Rate setting. Then just go over the render with the tool. It takes a while to figure out how much to sharpen and stuff, but it's a useful tool. It makes everything much crisper.