I like the concept and the pixel work, but I also think the piece has been lost within the detail and colour palette. At first I read it as rock instead of cloud. I think this might be down to the strength of your shades and the way you'd pixelled the texture. Seems I'm the only person with this view though, so I may be barking up the wrong tree.

Love it.

 Nice job !!

 Thanks for the thoughful critique. I will put these things into consideration when cleaning up this piece!

Whoa! Ambitious piece! Quite good already, but there is room for improves.

Mostly, the black in the city makes it appear like flatly pasted over a piece with good depth. It should have some 'aerial perspective', with softer tones in the distance, not too much darker than the darkest cloud shadows. Also it might use some relections. Second time I link this...

Then, dithering: it seems a bit pointless in the distance which reads as clear sky, but could have helped with the cloud textures instead. Very very little of it in any case!

Kind of looks like the city is on fire, but I really like this.

Clouds are leathery in places, but still a nice piece of work! 

Badass. Great concept... although I'm not overly fond of the clouds. Probably it's the way they're shaded, they look a little plasticine. And I feel like the lightning should probably lighten the clouds around it; it doesn't feel that luminous, as-is. But it's a great image, otherwise, I love the darkness of the city and how its architecture is mostly obscured and left to the imagination.