I would like to see a less extreme blending in the sky. For some reason the clouds look funny, like they were cut out and pasted onto the blue sky.
Be very careful about blending boundries. The mountains in the background have a dark halo near the top, and the foreground mountains have a light halo in the sky. It looks like what happens when you turn up local contrast enhacement too much.
The solutions I have found to these problems can be to: Lessen the exposure gap in certain areas, (such as the clouds); this can be done with more curve layers. And to be very careful about the borders of your layer masks. Use gradients when there are no sharp edges and make borders exactly follow the edges in the image. Tone masking seems to be a great techniqie that I am not yet any good at.
I find myself using many layers and masks, (probably too many), when working on a project such as this. Just stand back and ask yourself, "does this look right?"; strive to remove any artificial-looking effects.