I like...- The idea in general. A lot

- the colors and structure of the BG (did you do it yourself?)
I don't like...- some minor mistakes (see below)
You could improve...The opacity of the white layer could be brought down a little, although this is just personal preference. On the other hand, when there's a crack in the BG, there's no way paint is not interrupted by this crack. Just delete the white part that is directly above the fissure. You could also try to give the white layer a little nudge with the displace filter to give it more structure and therefor make it look like it's really painted on the rocky BG.
All in all ratingBeginner [-----------------[]------] Awesome
Further tips/commentsCan you give me the link to the brushes you used? The white stuff looks awesome.