It's a cool picture, but yeah they could have done with twisting his arm a bit less. I don't doubt they're capable, being super-agile and flexible (nudge nudge wink wink) space elves, but it does look a bit odd.
I also think they should have gone for the other helmet you get with that model, which is much cooler I think and more 'Dark Eldar'. I don't dislike the horns, but having them on the cover is a pretty big mis-representation of the army as a whole.
"Oh how awful, did he at least die painlessly? To shreds you say? Well, how's his Dracon holding up? To shreds you say? Very well then... Sad, sad, terrible gruesome news about my colleague Archon Mhu'bhutu." - 'The Feather', Dracon of the Bladed Lotus