This critique may turn out to be long and very detailed. I hope you won't mind that.
General impression: This picture sure is strong. Even though I first thought it's an octopus, I'm now really amazed by this drawing. I can't really tell whether this dragong is greedy or not because of his sleepily expression in it's face. But that it's laying on top of the pile of treasures lets me think it really doesn't want anyone to get all those jewellery. The drawing also has a really strong contrast thanks to the warm colors on the bottom (red and yellow) and the colder ones at the top (blue and purple). The drawing seems really detailed from the first look on and it's eye-catching.
Colors: As already mentioned, there's a nicely even amount of colder and warmer colors. Some brown and pink-purple, aswell as some blue and green jewellery make sure that it seems balanced even though 2/3 of the picture are filled with warm colors. Or well, you could almost say they are hot. The red really is strong. But that's what makes it outstanding from the yellow. Really nice to see since it happens to many people that they make transitions where there're none supposed to be. Since it's about the dragon right now, I need to mention that at some parts there's a bit too much yellow. Like on the outer side of the neck. It simply seems to reflect too much on this side. Mostly because there is almost no reflection on the other one. If the Dragon is not shiny or super reflecting, rather a bit less of light reflections. : ) Now about the upper part of the drawing. I am really amazed by how you made the yellow and blue melt! Need to confess, I am not sure if there's a light reflection or some flame like stuff to see, but it still looks good. Just... If it is a reflections of the gold and such, then I think the dragon would block some of the light. That's why it's a bit confusing that this yellow light follows exactly the shape of the dragon. The blue seems really strong, but that's fine since the whole picture has intense colors.
Shading: Okay, now about the shading. As I mentioned already... At first I thought it's an octopus. Some slaces are really bright at the edge so they looks a bit like suckers on the first look. But on the second look it's really well shaded. I like the treasures the most except at the very front of the picture, because they seem a bit too bright there. A bit depth missing I think. The stonewall in the background looks good too. But a bit like you used the almost same shape for all ledges and cliffs though. So may try to let the cracks go into a few more different directions. Other than that really great stones! So all in all it's great shaded. Most of what is bothering me may wouldn't have happened digitally. But we all know that when it comes to traditional art there are some limits when it comes to overcoloring and changing already done things.
Pose of the dragon: This pose sure is special: (Last time I mention it) Octopus. Because the limbs go into 5 directions it easily can be confusing. Or maybe it's just me and I have a predilection for Octopuses today. I need to say that the pose has it positives too! I like the way the dragon is laying on the pile of treassures. I don't think I saw such a pose within the last months, another thing: the dragon looks really relaxed, already from the fact that it's resting it's head on the wing.
Depending on what you wanted to draw it may failed or was a success. If the dragon is supposed to seem greedy then I need to say... It looks far too relaxed in my mind. But if the dragon is supposed to look simply satisfied with what it has, then it was a success. Because that's the way the dragon seems.
Okay, Hopefully this wasn't a too long critique for you. Don't forget, most of the things I mentioned may be personal likings/disliking. Still I hope that those 833 words were not wasted and turn out to be somehow useful for you!