My first impression? Wow - I never knew good old friendly Pokemon could be that kick ass and serious but Firecloud really made it.
At first I really love the angle / perspective of this pic. It's as if you'd crawl through the grass thinking "please don't notice me, please don't notice me" and when you look up this is what you see. The Background is kept unfocused and simple which only adds to the effect that the Houndoom in the foreground catches your attention even more. His sharp and dangerous glimpse together with this very great red light that emmits from his mouth makes me want to run fast - VERY fast. I also love the horns because they simply look brilliant and very detailed + the reflection of the red light adds to the atmosphere.
Houndoom never looked more kick ass yet still natural and frightening realistic to me.
Another part of the pic I really love is the background - it's kept simple but creates a great, yet mysterious atmosphere - strangely calm and peacful because of the night. The mountain remembers me of old chinese and japanese pictures and I guess that was intended to look so - together with the silhouettes of the other houndooms and the bright white moon as contrast it gives the picture a great depth - exactly because of the seperation from "simple" background and sharp, very detailed foreground. It's most probably the sight you would get if you would crawl through the grass, then look up just to look into those sharp, yet warning eyes, telling you to turn around and leave because this Pokemon will protect his pack and you better not try anything dumb.
Which adds to the dangerous-situation-fact is the other silhouette of the houndoom which slowoly approaches for backup. Also two other houndooms seem to be very interested in the newcommer and want to examine him.

Overall a very great piece of art from a very talented artist - you don't wanna mess with a Pokemon ever again if you looked at this pic!