Looks nice and 3D-ish if you're going for a cartoon effect. Like a little box. If you want it to float in the air I think it's ok. (but could use a few more details like Devernath said) If it will always be on the "ground" then you may want to just be rid of the shading at the bottom.
Good for some styles, could be better for others. Depends on what you're aiming for!