Kind of bland, actually. I would add something to make it more interesting. It looks like you just plopped the models from the website ontop of the logo.
Pretty much. I drew in that purple smoke that the witch doctors got going on, and used a lighting effect on the 3 characters; you may noticed the top half of their torsos are more illuminated than their lower leg areas.
But, yeah, what would you suggest to make it more interesting?
Your eye fights between trying to focus on the characters and trying to focus on the logo. All the lines in the background draw your eye up to the middle, and it draws your attention away from the real focus; the characters.
At they very least, make the logo significantly smaller.
Imagine what you could do with high contrast, low opacity layers of scenery taken from the concept art. I would add some thing that angles downward from the top corners and draws your eye to the characters (maybe they will have to shrink a little, not a big loss since they will look better smaller, with the polygons being less noticeable).
I'll throw together a basic mockup of something here in a second.
Obviously the red is where your cutouts go. Add some glow to them. Drop a texture under their feet also.
That is just really general outline of something I would do. (I didn't want to actually follow through and put in real images - this is your idea/wallpaper, I don't want to make it since its yours, hence the stand ins and poor logo drawing). I just threw in the first concept art I came to that looked both big and dark.
Then again, I tend to 'go big or go home' with sigs/wallpaper. My current sig is something like 29 layers.