Well, the entire thing looks about a stop underexposed to me. The image also looks a bit blue, but that could just be exposure as well. I'd try to brighten it, but watch the saturation on the reds when you do, since they'll get out of control very easily, and turn into blocks of saturated color where you can't see any detail. If that happens, play with the Hue/Saturation sliders for red, and use layer masks to get things back under control.