I immediately took to Nero, I liked playing as him from the beginning if I'm honest, and I had followed the series from 1 to 3 up until that point. I didn't really dwell too much on why Nero ate up most of the story as I had just assumed it was something similar to how MGS 2 had more Raiden than Snake.
Nero, to Me, was quite a likable character, I can't recall much of the actual storyline of DMC 4 as it's been so long since I've played it, but if I recall correctly Nero was a potent concoction of Love, hate, shame, frustration, confusion and cockiness. Which worked quite well, especially in contrast to Dante's slightly more calm and reserved demeanor.
Also, I LOVED his Devil Bringer ability, which really complimented the combat and helped keep fighting flowing neatly, as sometimes I would find Myself having to Stinger towards enemies to get to them in time, only to have the Stinger connect and thus shove the enemy further away from Me. It also really helped to promote Air combat.
Which is likely why DmC has a Devil Bringer-esque ability in the form of Dantes demon Rebellion arsenal.
tl;dr - You can rev his sword the way You would a motorcycle = Auto-Win. "CRAYZAY!"