Yes, a demon having a change of a heart isn't so emotional. And vergil starting the whole quest for power because of his mother's death isn't so deep. So is dante's understanding of his father's role and heritage, the importance of bonds after meeting lady and learning about her family errand. Just a shallow character description and development, while caring about humanity all of the sudden while being abused by humans with no obvious reason is logical and deep.
Nero wasn't one dimensional, The story of this game just took all 4 games and mashed it into some messy plot. Lilth gets shot Mundus shows no emotion walks to the demon gate gets power and send over half the city into limbo while only saying "you don't f*** with a god."
Not to mention Vergils complete OOC scenes.
*Hops on Sony Pony.* Onward my loyal legion of Nintendrones and Xbots! Ahh! My ding ding dong!
Thats because DMC is supposed to be a fantasy game where as this one takes a more realistic spin on things. Sure recently alot of games have been trying to take more realistic takes and making more humane characters but it still will never compare to DMC's original story.
Mundus in this game barely stands as an intimidating villain he just comes off as an evil banker until the last act when he actually shows his power.
As for the plot its pretty standard and the whole conflict with Dante and Vergil by the end of it is pretty much ripped straight from Assassin's Creed's Assassin and Templar conflict and even that feels rushed.