Its really good. I would love this mini myself. He looks so big and intimidating as well he should. Unfortunatly I have never seen him with another mini to compare his size. You have done a great job on this one. Maybe you could have made a single part of his body stand out with a seperate color to "catch the eye". for instanse making his face in pure white or something. That would make it work up close as well as from afar.
I like it, dark and evil, just the way it should be. I really like the lava feel of his body but I think that the armour could have been better and the blade of the sword would, in my oppinion, look better if it was painted a different colour than the armour, preferably something bright. Over all though, very nice Avatar!