pretty good job controlling the exposure, even though some portions of the cloud appear blown out on my monitor. good saturation in the colors. the border detracts slightly however (it's too dark and doesn't have any separation from the inner color)
Very good subject. Very dramatic illustration of power. It would be better IMO if the whites weren't blown. It feels to me like you gave it too much mid-tone contrast, or a bit too much effect in Curves. Back off just a little bit and it would be better, I think.