>>6114608i dont have deadpool but i do have BVS Batman. He wears a full body suit like deadpool and released about the same time i think. I want to say your reviewer was too afraid to move the arms up to their extreme out of fear of tearing fabric but i aint about that pussy life.
Pic related has left arm bent from the bottom of the joint and the right has it bending from the upside down position.
or maybe the deadpool figure has a quality to match his movie. i wouldnt doubt it being the true articulation. from my experiences hot toys figures usually do not have articulation matching other 1/6 companies especially if in tight clothing or exposed joints.
