As I said he could have been a promosing character,but he is actually powerful. That scene when he uses his Devil Bringer against the Savior was "woah".
He acts like Dante but isn't exactly a copy,he has waaay more angry issues.But you know,we already have a badass guy over here named Dante and one is enough,they could have given Nero,for example,a different personality,one that is a little bit more unique and not so Dante-like. Though,when it comes to temper he is different from Dante.
I saw his reaction differs from time to time from Dante's for example when encountering ladies.(here he reminds me of Vergil haha)