Well, of course Nero is something different. That's why they made him in the first place. To not give Dante even more power (imagine Dante with all his styles AND Devil Bringer, he would be unstoppable
).
Also to keep in the picture some of the character that Dante had in DMC3, cocky, arrogant stylish. Along with the DMC1 Dante who's serious but enjoys taunting his enemies to no end, who's the DMC4 Dante now.
Nero has some unique abilities, I imagine, Devil Bringer will allow him to access places which couldn't be accessed through normal conditions(because Dante can access anything, he's flying and walking to walls) just to make it different/interesting.
Also is something new and nice, but as Nowshin said we haven't seen Dante play using each Style one after the other while switching Devil Arms and guns at the same time