to be able to see danger and threats from all directions. to be able to see chakra veins and block them. to paralyze the whole persons ninjutsu and genjutsu and still having taijutsu to go meele is just amazing. and if u really look at it in a ninjas perspective. stealth, recon, offense and defense. the rinnegan and sharingan are amazing, but to see the devils eyes on neji who is now a jounin is also a sight to behold.